TY - CONF A1 - Topolniak, Ievgeniia A1 - Elert, Anna Maria A1 - Knigge, Xenia A1 - Cinar Ciftci, G. A1 - Radnik, Jörg A1 - Sturm, Heinz T1 - Direct laser surface micropatterning with polydopamine N2 - Inspired by the chemistry of mussel adhesive proteins, polydopamine (PDA) is one of the simplest and most versatile approaches to confer new functionalities to nearly any material surface. Moreover, PDA exhibits high potential for surface modification and diversified secondary reactions that makes it extremely interesting for a wide range of application including biomedical field, e.g., drug delivery, adhesives, cell adhesion, biosensing. PDA has undergone significant expansion in its applications and is one of the most attractive areas within the materials field. Nevertheless, PDA integration in microdevices is still constrained by poor spatial and temporal control of excited deposition methods. Herein, we demonstrate a novel maskless approach for PDA micropatterning based on Direct Laser Writing (DLW) that overcomes present limitations. The pattern is formed upon exposure of the dopamine solution by light produced by tightly-focused fs NIR laser that scans substrate surface accordingly to the selected pattern design. Neither strong oxidants, metal ions nor adjusting pH to alkaline is required by this technique. Our method achieves the PDA micropatterns with the spatial resolution of 0.8 µm, at least an order of magnitude smaller than what is possible with other PDA microplanning techniques. The here introduced PDA deposition technique will uniquely unravel applications of polydopamine and other catecholamine-based mussel-inspired materials in various multifunctional systems and microdevices (e.g., MEMS elements, microfluidics). Adjustment of MPL parameters revealed that the morphology and thickness of resulted PDA microstructures can be controlled by altering the laser power and its scanning velocity. As a result, it also enables the production of micropatterns with structural gradient. Apart from the glass substrate, we achieved PDA patterning at surfaces of different nature such as polychlorotrifluoroethylene, polydimethylsiloxane, polyethylene terephthalate, silicon wafers, and fluorinated glass coverslips. The chemical nature of PDA was confirmed by locally recorded vibrational and x-ray photoelectron spectra. To ensure post-modification potential of MPL deposited PDA we demonstrated one-step deposition of micropatterns with trypsin. Obtained bio-functionalised surface can be further applied as a protein sensing active microelement. Presented in this work DLW-based microfabrication technique and the possibilities for further PDA surface post-functionalization empowers advanced applications of this material in single-molecule bioassays, sensors and other complex microdevices. T2 - Swiss ePrint 2022 CY - Buchs, Switzerland DA - 05.09.2022 KW - Polydopamine KW - Two-photon polymerisation KW - Micropatterning PY - 2022 AN - OPUS4-56422 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Silbernagl, Dorothee A1 - Szymoniak, Paulina A1 - Tavasolyzadeh, Zeynab A1 - Sturm, Heinz A1 - Topolniak, Ievgeniia T1 - Interpenetrating networks with tuned thermal and mechanical properties N2 - Multiphoton lithography (MPL), an emerging microfabrication technique, shows great potential in a variety of applications ranging from tissue engineering to soft micro-robotics. Fabricated micro-objects often are expected to undergo shape morphing or bending. Furthermore, ensuring precise property tuning becomes detrimental for the functionality of MPL microstructures. Herein, we present novel MPL materials based on interpenetrating networks (IPNs), which effectively combine the advantages of acrylate and epoxy thermoset systems. A library of 3D MPL IPN microstructures with high 3D structural stability and tailored thermal and micromechanical properties is achieved. MPL laser velocity and fabrication power can be used to tune the morphology and therefore properties of IPN. New IPN microstructures with materials Young's moduli of 4 to 6 MPa demonstrate susceptibility to deformation with high to fully elastic response. Such soft elastic materials hold immense promise within morphable microsystems, soft micro-robotics and cell engineering applications. T2 - RSC Poster conference CY - Online meeting DA - 05.03.2024 KW - Multiphoton lithography KW - Interpenetrating polymer networks KW - AFM PY - 2024 AN - OPUS4-60060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Topolniak, Ievgeniia A1 - Hodoroaba, Vasile-Dan A1 - Braun, Ulrike A1 - Pfeifer, Dietmar A1 - Sturm, Heinz T1 - Reinforced UV curable cycloaliphatic epoxy oligosiloxane resin nanocomposite for coating applications N2 - Coating materials are nowadays often required to deliver not only sufficient barrier performance and suited optical appearance but a broad range of other functional properties. The incorporation of inorganic nanoparticles (NPs) is known to improve many key characteristics and provide new functionalities in polymer materials. Presented work aims to prepare and characterize an organic-inorganic coating material designed to bring together advantageous properties of hybrid materials and reinforcement effect delivered from the inorganic NPs embedment. Siloxane-based hybrid resins hold great advantages as coating materials as their properties can be tuned between those of polymers and those of glasses, thus, the compositions with superior thermal and mechanical properties can be achieved. We used Cycloaliphatic Epoxy Oligosiloxane (CEOS) resin as a polymeric matrix where the network formation was achieved by UV induced cationic polymerisation. Boehmite Alumina (BA) nanoparticles were added to CEOS resin as a reinforcing agent and resultant material was processed into films either by bar-coating or by spin-coating depending on further characterization procedure. Two different types of BA NPs, hydrophilic and organophilic, were used in order to assess the impact of particles surface on the resin characteristics. CEOS synthesis by condensation reaction was confirmed using 13C and 29Si NMR. Changes in CEOS photocuring process, resulting from particles incorporation, were monitored by real-time IR spectroscopy. At the same time, the thermal behaviour was evaluated by DSC and TGA methods. Morphology of the coatings was investigated by means of SEM operated in transmission mode. It was observed that BA presence increased the epoxy conversion degree and glass transition temperature. Material formulations providing best film characteristics were determined with regard to the particle type and loading. Compared to the hydrophilic nanoparticles, organophilic BA NPs yield superior overall performance of the foils. T2 - HYMA Conference CY - Sitges, Spain DA - 11.03.2019 KW - Cycloalyphatic epoxy oligosiloxane KW - Nanocomposite KW - Boehmite KW - Photocuring PY - 2019 AN - OPUS4-47641 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geyler, Paul A1 - Rabe, Torsten A1 - Mieller, Björn A1 - Léonard, Fabien T1 - Machine learning assisted evaluation of the shape of VIAs in a LTCC multilayer N2 - The introduction of the 5G technology and automotive radar applications moving into higher frequency ranges trigger further miniaturization of LTCC technology (low temperature co-fired ceramics). To assess dimensional tolerances of inner metal structures of an industrially produced LTCC multilayer, computer tomography (CT) scans were evaluated by machine learning segmentation. The tested multilayer consists of several layers of a glass ceramic substrate with low resistance silver-based vertical interconnect access (VIA). The VIAs are punched into the LTCC green tape and then filled with silver-based pastes before stacking and sintering. These geometries must abide by strict tolerance requirements to ensure the high frequency properties. This poster presents a method to extract shape and size specific data from these VIAs. For this purpose, 4 measurements, each containing 3 to 4 samples, were segmented using the trainable WEKA segmentation, a non-commercial machine learning tool. The dimensional stability of the VIA can be evaluated regarding the edge-displacement as well as the cross-sectional area. Deviation from the ideal tubular shape is best measured by aspect ratio of each individual layer. The herein described method allows for a fast and semi-automatic analysis of considerable amount of structural data. This data can then be quantified by shape descriptors to illustrate 3-dimensional information in a concise manner. Inter alia, a 45 % periodical change of cross-sectional area is demonstrated. T2 - DKG Jahrestagung 2019 CY - Leoben, Austria DA - 06.05.2019 KW - Machine Learning KW - LTCC multilayer KW - 5G PY - 2019 AN - OPUS4-48289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Agudo Jácome, Leonardo A1 - Mosquera Feijoo, Maria A1 - Nolze, Gert A1 - Rizzo, F. T1 - Nano-sized precipitates in an Fe-13Cr alloy formed under oxidizing water vapor atmosphere N2 - Oxidation of a Fe-13Cr alloy under water vapor at 600 °C produced a zone of nano-sized precipitation underneath the outside scale formed by iron oxides and Fe‒Cr spinel. The majority of the spinel layer shows a mixed orientation relationship to the ferritic matrix {100}α || {100}sp & <011>α || <001>sp. However, also the discovered precipitated particles are characterized by the same crystallographic orientation relationship to the respective ferritic parent grain. The habit of the precipitates is best described by a lath morphology with their main axis parallel to <100> of ferrite. Energy dispersive X-ray spectroscopy (EDX) and electron backscatter diffraction (EBSD) in an scanning electron microscope (SEM) have been applied to characterize the oxide layer in the micrometer scale. The clearly smaller precipitates were subsequently investigated by transmission electron microscopy (TEM). Specimens have been prepared by focused ion-beam (FIB) milling at an area previously characterized by EBSD. They cover the ferritic base material, but mainly the precipitation zone and the Fe‒Cr spinel layer. Energy filtered selected area diffraction (SAD) in the conventional (C)TEM and high-angle annular darkfield (HAADF) imaging in the scanning (S)TEM mode were employed in the characterization of the specimens. T2 - International Conference on Solid-Solid Phase Transformations in Inorganic Materials (PTM) 2015 CY - Whistler, British Columbia, Canada DA - 28.06.2015 KW - Precipitation KW - Oxidation KW - Microscopy KW - Topotactic transformation KW - Spinel PY - 2015 AN - OPUS4-42169 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mrkwitschka, Paul A1 - Mieller, Björn A1 - Rabe, Torsten A1 - Markötter, Henning T1 - Machine learning assisted characterization of a Low Temperature Co-fired Ceramic (LTCC) module measured by synchrotron computed tomography. N2 - The 5G technology promises real time data transmission for industrial processes, autonomous driving, virtual and augmented reality, E-health applications and many more. The Low Temperature Co-fired Ceramics (LTCC) technology is well suited for the manufacturing of microelectronic components for such applications. Still, improvement of the technology such as further miniaturization is required. This study focuses on the characterization of inner metallization of LTCC multilayer modules, especially on the vertical interconnect access (VIA). Critical considerations for this characterization are delamination, pore clustering in and at the edge of the VIA, deformation, and stacking offset. A LTCC multilayer consisting of a glassy crystalline matrix with silver based VIAs was investigated by synchrotron x-ray tomography (CT). The aim of this study is to propose a multitude of structural characteristic values to maximize the information gained from the available dataset. Data analysis has been done with the open source software ImageJ as well as several additional plugins. The high-resolution CT data was evaluated through 2D slices for accessibility reasons. The segmentation of all 2000 slices to assess the different regions e.g. pores, silver and glass ceramic was done by a supervised machine learning algorithm. A quantitative evaluation of shape, deformation, and porosity of the VIA with respect to its dimensions is presented and the suitability of the characterization approach is assessed. T2 - 54. Metallographie Tagung CY - Online meeting DA - 16.09.2020 KW - Machine Learning KW - LTCC KW - Synchrotron Tomography PY - 2020 AN - OPUS4-51299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stargardt, Patrick A1 - Junge, P. A1 - Greinacher, M. A1 - Kober, D. A1 - Mieller, Björn T1 - Bulk vs thermal sprayed alumina for insulation applications: A comparison of electrical and dielectrical properties N2 - Additive manufacturing (AM) processes are opening new design possibilities for large scale electrical devices such as power generators. Conventional manufacturing methods use copper rods which are wrapped, vacuum impregnated, bend and welded. These processes are labor-intensive and time-consuming. The introduction of AM methods for manufacturing the copper conductor and electrical insulation can reduce the size of the generator head, the most complex part of the generator. In this study, the electrical and dielectrical properties of additively deposited ceramic layers are investigated and compared with the properties of conventionally fabricated bulk ceramics. The ceramic layers are thermally deposited by atmospheric plasma spraying of a commercially available alumina powder. Bulk ceramics are fabricated by dry pressing and sintering of the same powder. Microstructure and porosity were analyzed by scanning electron microscopy (SEM). Electrical and dielectrical properties such as DC resistance, dielectric strength, dielectric loss, and relative permittivity were determined according to the standards. The microstructures of sprayed and sintered alumina show significant differences with respect to grain form and porosity. The density of the bulk ceramic is lower than the density of the sprayed layer due to the coarse particle size (d50 = 33 μm). Therefore, data from dense samples of the same chemical composition but lower particle size alumina powder were used for comparison. T2 - Keramik 2022 CY - Online meeting DA - 07.03.2022 KW - High Voltage Insulation KW - Thermal Spray KW - Dielectric Spectroscopy KW - Atmospheric Plasma Spraying PY - 2022 AN - OPUS4-54446 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Manzoni, Anna Maria A1 - Mohring, W. A1 - Hesse, René A1 - Agudo Jácome, Leonardo A1 - Stephan-Scherb, C. T1 - Early Material Damage in Equimolar CrMnFeCoNi in Mixed Oxidizing/Sulfiding Hot Gas Atmosphere N2 - The use of more and more varied fuels implies an increased list of criteria that need to be addressed when choosing a material for a combustion chamber and its supply pipes. The materials must be very resistant against corrosion, especially when the process takes place at temperatures above 500°C. In this work the influence of SO2 on the surface of the “Cantor alloy” is investigated. T2 - HEA-Symposium "Potential for industrial applications" CY - Dresden, Germany DA - 12.05.2022 KW - High entropy alloy KW - Corrosion KW - Sulfiding KW - Transmission electron microscopy PY - 2022 AN - OPUS4-55397 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stargardt, Patrick A1 - Bresch, Sophie A1 - Walter, P A1 - Stargardt, Patrick A1 - Höhne, Patrick A1 - Moos, R A1 - Mieller, Björn T1 - Comparison of design concepts for ceramic oxide thermoelectric multilayer generators N2 - Multilayer thermoelectric generators are a promising perspective to the conventional π-type generators. Ceramic multilayer technology is well established for production of microelectronics and piezo-stacks. Key features of ceramic multilayer technology are full-automation, cost-effectiveness, and the co-firing of all materials in one single step. This requires similar sintering temperatures of all used materials. The development of multilayer thermoelectric generators is a subject of current research due to the advantages of this technology. One of the challenges is the compatibility of the different materials with respect to the specific design. The presented study compares three different designs of multilayer generators based on a given set of material properties. Dualleg, unileg and transverse multilayer generators are compared to conventional π-type generators., the designs are evaluated regarding the expected maximum output power and power density using analytical calculations and FEM simulations. Additionally, the complexity of the production process and material requirements are assessed and design optimizations to simplify production are discussed. Besides the theoretical aspects, unileg multilayer generator prototypes were produced by tape-casting and pressure-assisted sintering. These prototypes are compared to other multilayer generators from literature regarding the power factors of the used material system and the power density. Improvements of the power output by design optimizations are discussed T2 - 18th European Conference on Thermoelectrics CY - Barcelona, Spain DA - 13.09.2022 KW - Thermoelectric oxides KW - Thermoelectric generator design PY - 2022 AN - OPUS4-55820 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Musl, O. A1 - Falkenhagen, Jana A1 - Sumerskii, I. A1 - Sulaeva, I. A1 - Mahler, A. K. A1 - Rosenau, T. A1 - Potthast, A. T1 - Mapping the Hydrophobic Composition of Lignosulfonates with 2D HIC-SEC aq. Liquid Chromatography N2 - 2D-LC provides in-depth information on the complex composition of lignosulfonates – information hitherto inaccessible by state-of-the-art lignin analytics. Analysis of 12 industrial lignosulfonates revealed considerable differences in their composition and functional dispersity - properties that are crucial for lignosulfonate usage T2 - Sustainable Materials Research Summit 2022, S.M.A.R.T CY - Vancouver, Canada DA - 07.08.2022 KW - Lignosulfonate KW - Lignin KW - Amphiphilicity KW - Hydrophobic interaction KW - Chromatography (HIC) KW - Size-exclusion chromatography (SEC) KW - Functionality type distribution KW - Two-dimensional liquid chromatography (2D-LC) KW - Molar mass distribution PY - 2022 AN - OPUS4-55510 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Miliūtė, Aistė A1 - Bustamante, Joana A1 - Mieller, Björn A1 - Stawski, Tomasz A1 - George, Janine A1 - Knoop, F. T1 - High-quality zirconium vanadate samples for negative thermal expansion (NTE) analysis N2 - Zirconium vanadate (ZrV2O7) is a well-known negative thermal expansion (NTE) material which exhibits significant isotropic contraction over a broad temperature range (~150°C < T < 800°C). The linear thermal expansion coefficient of ZrV2O7 is −7.1×10-6 K-. Therefore, it can be used to create composites with controllable expansion coefficients and prevent destruction by thermal shock. Material characterization, leading to application, requires pure, homogenous samples of high crystallinity via a reliable synthesis route. While there is a selection of described syntheses in the literature, it still needs to be addressed which synthesis route leads to truly pure and homogenous samples. Here, we study the influence of the synthesis methods (solid-state, sol-gel, solvothermal) and their parameters on the sample's purity, crystallinity, and homogeneity. The reproducibility of results and data obtained with scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric analysis (DSC/TGA) were analyzed extensively. The sol-gel method proves superior to the solid-state method and produces higher-quality samples over varying parameters. Sample purity also plays an important role in NTE micro and macro-scale characterizations that explain the impact of porosity versus structural changes. Moreover, we implement ab-initio-based vibrational computations with partially treated anharmonicity (quasi-harmonic approximation, temperature-dependent effective harmonic potentials) in combination with experimental methods to follow and rationalize the negative thermal expansion in this material, including the influence of the local structure disorder, microstructure, and defects. Khosrovani et al. and Korthuis et al., in a series of diffraction experiments, attributed the thermal contraction of ZrV2O7 to the transverse thermal motion of oxygen atoms in V-O-V linkages. In addition to previous explanations, we hypothesize that local disorder develops in ZrV2O7 crystals during heating. We are working on the experimental ZrV2O7 development and discuss difficulties one might face in the process as well as high-quality sample significance in further investigation. The obtained samples are currently used in the ongoing research of structure analysis and the negative thermal expansion mechanism. T2 - 16th International conference on materials chemistry (MC16) CY - Dublin, Ireland DA - 03.07.2023 KW - NTE KW - Sol-gel KW - Solid-state KW - Ab-initio KW - TDEP PY - 2023 AN - OPUS4-58134 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winckelmann, Alexander A1 - Hoffmann, V. A1 - Morcillo, Dalia A1 - Agudo Jácome, Leonardo A1 - Leonhardt, Robert A1 - Richter, Silke A1 - Recknagel, Sebastian A1 - Abad Andrade, Carlos Enrique T1 - Investigation of degradation of the aluminum current collector in lithium-ion batteries by glow-discharge optical emission spectroscopy N2 - Lithium-ion batteries (LIBs) are one technology to overcome the challenges of climate and energy crisis. They are widely used in electric vehicles, consumer electronics, or as storage for renewable energy sources. However, despite innovations in batteries' components like cathode and anode materials, separators, and electrolytes, the aging mechanism related to metallic aluminum current collector degradation causes a significant drop in their performance and prevents the durable use of LIBs.[1] Glow-discharge optical emission spectroscopy (GD-OES) is a powerful method for depth-profiling of batteries' electrode materials. This work investigates aging-induced aluminum deposition on commercial lithium cobalt oxide (LCO) batteries' cathodes. The results illustrate the depth-resolved elemental distribution from the cathode surface to the current collector. An accumulation of aluminum is found on the cathode surface by GD-OES, consistent with results from energy-dispersive X-ray spectroscopy (EDX) combined with focused ion beam (FIB) cutting. In comparison to FIB-EDX, GD-OES allows a fast and manageable depth-profiling. Results from different positions on an aged cathode indicate an inhomogeneous aluminum film growth on the surface. The conclusions from these experiments can lead to a better understanding of the degradation of the aluminum current collector, thus leading to higher lifetimes of LIBs. T2 - European Winter Conference on Plasma Spectrochemistry (EWCPS 2023) CY - Ljubljana, Slovenia DA - 29.01.2023 KW - Lithium-ion batteries KW - Aging mechanisms KW - Depth-profiling PY - 2023 AN - OPUS4-56992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weinel, Kristina A1 - Hesse, René A1 - Agudo Jácome, Leonardo A1 - Gonzalez-Martinez, I. T1 - Complex artificial features on a TEM transparent membrane N2 - The phenomenon of expelling nanomaterial from microparticles of different materials, such as Au, WO3 or B2O3 under the influence of a convergent electron beam (CB) of a transmission electron microscope (TEM) was reviewed by Ignacio Gonzalez-Martinez [1]. Converging the e-beam in a TEM means that a high amount of energy enters the microparticle at a very local place and interact with the matter. Obviously, during the convergent beam protocol, no imaging with the electron beam is possible, but at the end, nanoparticles with different appearances lie down next to the microparticle while its size is reduced. Hence, there is a blind spot in the observation, which we want to fill, as we want to help clarify the nature of the expelling phenomenon. One hypothesis that explains the phenomenon is the so-called damage (of the microparticle) induced by an electric field (DIEF). Within this theory, the material is ionized and expelled in form of ionic waves. Our aim is therefore to fabricate specimens with artificial microlandscapes, as schematically exemplified in figure 1a), using the focused ion beam (FIB) and micromanipulators, as experimental setups to follow the paths of the expelled material. As a first step towards the fabrication of such specimen, we make experimental feasibility studies for each fabrication method, FIB structuring with Ga+ ion beam and micromanipulated microparticle deposition. Bridges (gray regions in Fig. 1) are created by milling a commercially available electron transparent membrane (silicon oxide or carbon) of a Cu-TEM grid. Platinum or carbon walls (blue features in Fig. 1) are built to stand on those bridges. Microparticles (yellow sphere in Fig. 1) of gold or other material are deposited in the center of the bridges. Figure 2a) shows four square holes (black area) and between them the residual silicon oxide membrane bridges (dark grey). On top of the bridges, walls (light grey) are deposited. The width of the bridges is different, the walls overlap the holes as well as the distance between the walls is very small, so these and other parameters need to be optimized. Figure 2b) shows a square hole (black) with bridges (white) on the right side on top of a carbon membrane (grey). There are still some obstacles which needs to be eliminated. For instance, the deposition process of the walls is not reliable as visible at the wall on top where a hole arises instead of a wall. These studies are still in progress and the results are further discussed in terms of the applicability for the DIEF experiment in the TEM. T2 - 4th EuFN and FIT4NANO Joint Workshop / Meeting CY - Vienna, Austria DA - 27.09.2021 KW - Transmission electron microscope (TEM) KW - Sample preparation KW - Micromanipulation KW - Focussed ion beam growth KW - Nano-landscape PY - 2021 AN - OPUS4-58259 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas A1 - Rosu, Dana A1 - Ortel, Erik A1 - Kraehnert, R. A1 - Hodoroaba, Vasile-Dan T1 - Measurement of Porous TiO2 Layers with spectroscopic ellipsometry – a multi-method study N2 - By means of an effective medium (EMA) based approach, it is possible to use spectroscopic ellipsometry to determine the mixing ratios between air and material in porous dielectrics and calculate a quantitative value of the porosity for these materials. As this method is model-based, it is very difficult to provide a quantitative measure for the accuracy of porosity values determined by this method. Valuable additional information can often be obtained by combining ellipsometry with other complementary methods. In the present study, the ellipsometry results were validated by Electron Probe Microanalysis (EPMA) with the option of layer analysis (by the socalled “STRATAGem” approach), gravimetry, and electron microscopy. We analysed porous TiO2 thin layers synthesised by means of a template synthesis approach (evaporation induced self assembly). Ellipsometry measurements on porous samples are difficult to analyse due to the complexity of the models necessary. Often it is difficult to decide if the measured data contains enough information to successfully determine the target quantities (mixing ratio, dielectric function of the matrix material). One method to decrease the complexity of the fit and therefore use the measurement data most efficiently is a multi-sample analysis. In the present case, multi-sample analysis was used for determining the porosity factors of the individual layers while using one common set of dielectric function values for the matrix in all cases. While the results of the fit analysis in this case can be used to show the feasibility and also the limitations of the multi-method approach, the porosity values themselves show a promising agreement between the independent methods. It can therefore be concluded that determining porosity values with ellipsometry is in accordance to other methods to the level of accuracy provided by the complementary methodologies. T2 - International conference on spectroscopic ellipsometry (ICSE-7) CY - Berlin, Germany DA - 06.06.2016 KW - Spectroscopic Ellipsometry KW - Electron Microscopy KW - Multi-method Metrology KW - Porous Materials KW - Thin Films KW - Titanium Dioxide PY - 2016 AN - OPUS4-37202 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gawek, Marcel A1 - Madkour, Sherif A1 - Hertwig, Andreas A1 - Schönhals, Andreas T1 - Growth Kinetics and Molecular Mobility of Irreversibly Adsorbed Layers in Thin Polymer Films N2 - In well-annealed thin polymer films, with non-repulsive polymer/substrate interactions, an irreversibly adsorbed layer is expected to form. These adsorbed layers have shown great potential for technological applications. However, their growth kinetics and molecular dynamics are still not fully understood. This is partially due to the hard accessibility of these layers in thin films. Here, the irreversibly adsorbed layers of homopolymer thin films are revealed by solvent-leaching experiments. First, the growth kinetics of these layers is investigated as a function of annealing times and original film thickness. The thickness, topography and quality of the adsorbed layer is controlled with Atomic Force Microscopy (AFM). Secondly, the molecular mobility of the adsorbed layer is investigated with Broadband Dielectric Spectroscopy (BDS). A recently developed nanostructured capacitor is employed to measure the adsorbed layers with a free surface layer. The results are quantitatively compared and discussed with respect to recently published work. T2 - Spring Meeting of German Physical Society CY - Berlin, Germany DA - 12.03.2018 KW - Thin polymeric films KW - Dielectric spectroscopy PY - 2018 AN - OPUS4-44489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gawek, Marcel A1 - Hertwig, Andreas A1 - Schönhals, Andreas T1 - Growth Kinetics and Molecular Mobility of Irreversibly Adsorbed Layers in Thin Polymer Films N2 - In well-annealed thin polymer films, with non-repulsive polymer/substrate interactions, an irreversibly adsorbed layer is formed. These adsorbed layers have shown enormous potential for technological applications. The growth kinetics and molecular dynamics of these buried layers in thin films are still not fully investigated due to the hard accessibility. Here, the irreversibly adsorbed layers of homopolymer thin films are revealed by solvent-leaching experiments. The growth kinetics of these layers is investigated as a function of original film thickness and annealing times. The thickness, topography and quality of the adsorbed layer is determined with Atomic Force Microscopy (AFM) and spectroscopic ellipsometry. Additionally, the molecular mobility of the adsorbed layer is investigated with Broadband Dielectric Spectroscopy (BDS). A recently developed nanostructured capacitor (NSC) is employed to measure the adsorbed layers with a free surface layer depending on annealing and solvent-leaching time. The results are quantitatively compared and discussed with respect to recently published work. T2 - Spring Meeting of German Physical Society CY - Regensburg, Germany DA - 31.03.2019 KW - Adsorbed layer KW - Thin polymeric films PY - 2019 AN - OPUS4-47767 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hennersdorf, Felix A1 - Weltschev, Margit A1 - Hertwig, Andreas T1 - ATR Investigations into the effect of ageing on HD-PE heating oil storage tanks after a service life of more than 30 years N2 - Heating oil storage tanks made of polyethylene grades have been on the market in Germany since the early 1970s. To ensure safety, their replacement is recommended by tank manufacturers after a period of 30 years. Polyethylene is subject to ageing by alteration of the properties during its life cycle. The degree of degradation and the nature of the process mainly depend on the chemical alteration of the polyethylene, the wall thickness of the tank and the environmental conditions. There are no data available on the long-term behaviour of the polyethylene grades, especially after a service life of more than 30 years. The aim of this investigation was to find a suitable test method to determine the factual degree of damage in comparison to the uncontaminated polyethylene grades. Material data of the used polyethylene grades are available because the BAM was the competent authority for the tests and expert reports for the approval of these tanks until the middle of the 1990s. Therefore, tank sections from the bottom, the shell and the roof of 22 individual storage tanks produced of polyethylene grades A and B have been examined by Melt Flow Rate (MFR) and Attenuated Total Reflectance (ATR). Their service life was in the range between 20 and 41 years. The MFR measurements of the tank sections showed differences in the values depending on the weight which was used (5 kg or 21.6 kg). An increase of the MFR was determined for the samples of polyethylene grade A, whereas a reduction of the MFR values was measured for most samples of polyethylene grade B. This grade is mainly subject to the internal ageing by cross-linkages, increased degree of branched molecules and loss of the plasticizer. ATR analysis exhibits an absorption band at 909 cm‒1 predominantly in samples of polyethylene grade A indicating chain scission and concomitantly formed terminal vinyl groups. This absorption band can be used for the characterization of the ageing of the polyethylene grades. T2 - EUROCORR 2019 CY - Sevilla, Spain DA - 09.09.2019 KW - Heating oil tanks KW - Polyethylene KW - Ageing KW - Service life PY - 2019 AN - OPUS4-49000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ermilova, Elena A1 - Hertwig, Andreas A1 - Beck, Uwe A1 - Schneider, S. A1 - Peters, S. T1 - Standardization of spectroscopic ellipsometry as GUM-compliant accredited measurement method N2 - Ellipsometry has become a powerful measurement tool in semiconductor industry since the sixties of the last century. Early standardization activities focused exclusively on SiO2/Si (ASTM F 576-01, SEMI 3624). The first generic standard dealing with ellipsometry is DIN 50989-1:2018 Ellipsometry – Part 1: Principles. Standardization is a prerequisite for accreditation according to DIN EN ISO/IEC 17025 and the evaluation of uncertainty budgets. T2 - 8th International conference on spectroscopic CY - Barcelona, Spain DA - 26.05.2019 KW - Standardization of Ellipsometry KW - GUM-compliance KW - Uncertainty budgets KW - Bulk material PY - 2019 AN - OPUS4-48348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sachse, René A1 - Hertwig, Andreas A1 - Kraehnert, R. A1 - Hodoroaba, Vasile-Dan T1 - Analysis of elemental composition and porosity of mesoporous IrOx-TiOx thin films by SEM/EDS N2 - Porous materials play an important role in several fields of technology, especially for energy applications like photovoltaics, electrolysis or batteries. The activity of porous films is affected by properties like porosity, film thickness, chemical composition of the material as well as the crystallinity of the framework. The complex morphology of such porous films constitutes a challenge even for modern analytical techniques and requires new approaches employing the combination/complementation of data of different analytical methods. In this contribution we characterize thin mesoporous iridium-titanium mixed oxide film properties by Electron Probe Microanalysis (EPMA) with energy dispersive X-ray spectroscopy (EDS) at an SEM. T2 - EMAS 2019 - 16th European Workshop on MODERN DEVELOPMENTS AND APPLICATIONS IN MICROBEAM ANALYSIS CY - Trondheim, Norway DA - 19.05.2019 KW - Electron probe microanalysis (EPMA) KW - Iridium-titanium mixed oxides KW - Spectroscopic ellipsometry KW - Mesoporous thin films PY - 2019 AN - OPUS4-48769 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Müller, Kai A1 - Mirabella, Francesca A1 - Knigge, Xenia A1 - Weise, Matthias A1 - Sahre, Mario A1 - Wasmuth, Karsten A1 - Voss, Heike A1 - Hertwig, Andreas A1 - Krüger, Jörg A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan T1 - Chemical and topographical changes upon sub-100-nm LIPSS formation on titanium alloy N2 - Laser-induced periodic surface structures (LIPSS) have gained remarkable attention as they represent a universal phenomenon that is often accompanying laser-processing. Such LIPSS enable a large variety of different surface functionalizations for applications in the fields of optics, fluidics, tribology, or medicine. Moreover, so-called “high spatial frequency LIPSS” (HSFL) provide an appealing and straightforward way for surface nanostructuring featuring spatial periods even below 100 nm – far beyond the optical diffraction limit. However, the imposed surface functionalities are usually caused by both, topographic and chemical surface alterations. For exploring these effects in detail, multi-method characterizations were performed here for HSFL on processed Ti- 6Al- 4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm wavelength, ~1 ps pulse duration, 1 – 400 kHz pulse repetition rate) under different laser and scan processing conditions. The sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), stylus profilometry (SP), and white light interference microscopy (WLIM), as well as near-surface chemical analyses by X-ray photoelectron spectroscopy (XPS), hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results allow to qualify the laser ablation depth, the geometrical HSFL characteristics and provide detailed insights into the depth extent and the nature of the ps-laser-induced near-surface oxidation. Significance for medical applications will be outlined. T2 - E-MRS Spring Meeting 2023 CY - Strasbourg, France DA - 29.05.2023 KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrashort laser processing KW - Hard X-ray photoelectron spectroscopy (HAXPES) KW - Time-offlight secondary ion mass spectrometry (ToF-SIMS) KW - Ti6Al4V alloy PY - 2023 AN - OPUS4-58531 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas A1 - Rosu, Dana-Maria A1 - Ortel, Erik A1 - Hodoroaba, Vasile-Dan A1 - Krähnert, R. T1 - Measurement of porous TiO2 layers with spectroscopic ellipsometry - a multi-method study N2 - By means of an effective medium (EMA) based approach, it is possible to use spectroscopic ellipsometry to determine the mixing ratios between air and material in porous dielectrics and calculate a quantitative value of the porosity for these materials. As this method is model-based, it is very difficult to provide a quantitative measure for the accuracy of porosity values determined by this method. Valuable additional information can often be obtained by combining ellipsometry with other complementary methods. In the present study, the ellipsometry results were validated by Electron Probe Microanalysis (EPMA) with the option of layer analysis (by the socalled “STRATAGem” approach), gravimetry, and electron microscopy. We analysed porous TiO2 thin layers synthesised by means of a template synthesis Approach (evaporation induced self assembly). Ellipsometry measurements on porous samples are difficult to analyse due to the complexity of the models necessary. Often it is difficult to decide if the measured data contains enough information to successfully determine the target quantities (mixing ratio, dielectric function of the matrix material). One method to decrease the complexity of the fit and therefore use the measurement data most efficiently is a multi-sample analysis. In the present case, multi-sample analysis was used for determining the porosity factors of the individual layers while using one common set of dielectric function values for the matrix in all cases. While the results of the fit analysis in this case can be used to show the feasibility and also the limitations of the multi-method approach, the porosity values themselves show a promising agreement between the Independent methods. It can therefore be concluded that determining porosity values with ellipsometry is in accordance to other methods to the level of accuracy provided by the complementary methodologies. T2 - ICSE-7, 7th International Conference on Spectroscopic Ellipsometry CY - Berlin, Germany DA - 5.6.2016 KW - Spectroscopic ellipsometry KW - Electrolysis KW - Catalysis KW - Thin film metrology KW - Porous materials PY - 2016 AN - OPUS4-39940 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosu, Dana-Maria A1 - Hertwig, Andreas A1 - Beck, Uwe T1 - The accuracy and reproducibility in thickness determination of thin films using SE N2 - Maintaining a consistent product quality is critical for the thin film industry. Therefore, the development of highly accurate protocols able to detect variations and nonidealities in manufactured thin film devices is essential and helps improve production quality and decrease manufacturing costs. The present work will discuss the accuracy and reproducibility in the determination of the thickness of thin films relevant for optoelectronic industry using spectroscopic ellipsometry, starting with the importance of set-up calibration, the need for very well defined calibration standards suitable for real devices and not least, the importance of accurate data analysis. As ellipsometry is an indirect method and theoretical modelling is needed to obtain the desired information regarding the investigated samples (e.g. thickness, roughness, optical constants), the model uncertainty has to be discussed and taken into account. If for ideal samples consisting of single layers with well-known optical constants the determination of thickness and roughness is straight forward and pretty accurate, for real samples, more complex theoretical models are needed and extracting accurate information regarding the samples can be very challenging. With careful calibration and a multidisciplinary approach, a combined measurement methodology can be developed enabling reliability, comparability, and accuracy. For production-relevant operation, maintaining the ease of use and scalability of ellipsometry as a technique can also be retained. T2 - EOSAM (European Optical Society Annual Meeting) CY - Berlin, Germany DA - 26.09.2016 KW - Spectroscopic ellipsometry KW - Thin films KW - Film thickness determination KW - Uncertainty PY - 2016 AN - OPUS4-38109 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sachse, René A1 - Bernsmeier, D. A1 - Hertwig, Andreas A1 - Hodoroaba, Vasile-Dan A1 - Kraehnert, R. T1 - Spectroscopic ellipsometry for the determination of thickness and porosity of mesoporous metal oxide films N2 - Thin mesoporous metal oxide films are versatile and attractive candidates for several energy applications like photovoltaics, electrolysis or batteries. Due to their high surface area and ordered pore structure, mesoporous metal oxides demonstrate higher activities. The performance of the porous films is affected by properties like size and shape of the mesopores as well as the crystallinity of the framework. The exact determination and metrological evaluation of the complex morphology of thin mesoporous films requires a new analytical approach employing to combined data of different analytical methods. In this contribution we present a novel evaluation procedure for spectroscopic ellipsometry (SE) to analyse thin mesoporous iridium oxide films. Mesoporous iridium oxide films were prepared via dip-coating of a solution containing a triblock-copolymer as structure directing agent and an iridium precursor in ethanol. Deposited films were calcined in air at temperatures between 300 and 600 °C. Their morphology was studied with SEM and an electron probe microanalysis (EPMA)and correlated via SE with a Bruggeman effective medium approximation (BEMA). The developed SE model described the film thickness as well as the porosity. Figure 1a shows a top-view SEM image of mesoporous IrO2 film calcined at 375 °C. The image reveals that the films exhibit a well-ordered mesopore structure with an average pore diameter of 16 nm and a periodic distance between pore centres of 24 nm (FFT inset). Figure 1b is a parity plot of film thicknesses determined by cross-section SEM versus SE of IrO2 film samples prepared at different calcination temperatures. The porosity from the SE model is in good agreement to the porosity values obtained by EPMA. The contribution will assess in detail the novel approach to analyse the morphology and porosity of thin metal oxide films with spectroscopic ellipsometry. Moreover, the advantages of the new developed approach will be discussed as well as combination of datasets from multiple measurements to development new methods for innovative energy technologies. T2 - 30. Deutsche Zeolith-Tagung und Jahrestreffen der ProcessNet-Fachgruppe Adsorption CY - Kiel, Germany DA - 28.02.2018 KW - Mesoporous materials KW - Iridium oxide films KW - Electro catalyst KW - Spectroscopic ellipsometry KW - Thin film metrology KW - Multi-sample analysis PY - 2018 AN - OPUS4-45101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas A1 - Omar, Hassan A1 - Gawek, Marcel A1 - Madkour, Sherif A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Determining thermal transitions in thin polymer layers by means of spectroscopic ellipsometry N2 - Thin polymer layers have enormous technical significance as polymer coatings on materials are very cost-effective for tailoring properties of surfaces. Apart from technical aspects in their use, thin polymer layers can be used to determine dimensional aspects in properties of material, such as confinement effects. In this work, we investigated several different polymer layer materials and determined their glass transition region by means of temperature-dependent spectroscopic ellipsometry. We have optimised our fitting procedure of the ellipsometric data produced in temperature ramp experiments. By this, we could measure the dependence of Tg on the layer thickness in a wide variety of thickness values, proving the existence of confinement effects in the investigated systems. We compare numerical methods for determining the location of the glass transition and discuss the possibilities of different analysis methods when determining thermal transitions. We also discuss the simultaneous existence of these transitions and annealing effects and the implications on the accuracy of the determined data. T2 - 12th Workshop Ellipsometry 2023 CY - Prague, Czech Republic DA - 18.09.2023 KW - Thin Films KW - Polymers KW - Ellipsometry KW - Themal Transitions PY - 2023 AN - OPUS4-58413 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Omar, Hassan A1 - Szymoniak, Paulina A1 - Hertwig, Andreas A1 - Schönhals, Andreas T1 - Investigations of Ultrathin Polymer Films Supported on Inorganic Substrates N2 - Interactions between a polymer and a substrate interface play a vital role in understanding the improvement in thin film material properties as well as serving as a model for nanocomposites. For any non-repulsive polymer-substrate interactions, polymer segments form an irreversibly adsorbed layer and show a slowdown in the glassy dynamics and thus an increase in the thermal glass transition temperature compared to the bulk-like values. The growth kinetics of the adsorbed layer showed a deviation for both poly (bisphenol-A carbonate) (PBAC) and polysulfone (PSU), two bulky polymers containing a functional group (phenyl ring) in the backbone. T2 - Royal Society of Chemistry (RSC) Online Poster Conference CY - Online meeting DA - 05.03.2024 KW - Adsorbed Layer KW - Thin Films KW - Atomic Force Microscopy KW - Ellipsometry PY - 2024 AN - OPUS4-59625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Knigge, Xenia A1 - Müller, Kai A1 - Mirabella, Francesca A1 - Sahre, Mario A1 - Weise, Matthias A1 - Voss, Heike A1 - Hertwig, Andreas A1 - Wasmuth, Karsten A1 - Mezera, Marek A1 - Krüger, Jörg A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan T1 - Chemical and topographical analyses of ps-laser generated HSFL on titanium alloy N2 - Laser-induced periodic surface structures (LIPSS) enable a large variety of different surface functionalizations for applications in the fields of optics, fluidics, tribology, or medicine. Moreover, high spatial frequency LIPSS (HSFL) provide an appealing and straightforward way for the generation of surface nanostructures featuring spatial periods even below 100 nm – far beyond the optical diffraction limit. However, the imposed surface functionalities are usually caused by both, topographic and chemical surface alterations. For exploring these effects in detail, multi-method characterization was performed here for HSFL processed on Ti-6Al-4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm wavelength, ~1 ps pulse duration, 1 – 400 kHz pulse repetition rate) under different scan processing conditions. The subsequent sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), stylus profilometry (SP), as well as near-surface chemical analyses by X-ray photoelectron spectroscopy (XPS), hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results allow to qualify the laser ablation depth, the geometrical HSFL characteristics and provide detailed insights into the depth extent and the nature of the ps-laser-induced near-surface oxidation arising from the laser-processing in ambient air and into the relevance of heat-accumulation effects at high pulse repetition rates. Moreover, the direct comparison of the HAXPES and XPS data reveals the role of surface-covering organic contaminants adsorbed from the ambient atmosphere without ion-sputter depth profiling. Furthermore, reduction of the oxides by sputtering can be avoided. T2 - SPIE Photonics Europe 2024 Conference, Symposium "Lasers and Photonics for Advanced Manufacturing" CY - Strasbourg, France DA - 07.04.2024 KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrafast laser processing KW - Nanostructures KW - Chemical analyses PY - 2024 UR - https://spie.org/photonics-europe/presentation/Chemical-and-topographical-analyses-of-ps-laser-generated-high-spatial/13005-69#_=_ AN - OPUS4-59853 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Barnefske, Lena A1 - Petersen, Andreas A1 - Heidmann, Gerd A1 - Sturm, Heinz T1 - Development of a self-healing silicone rubber for high-voltage cable accessories N2 - One of the biggest problems in high-voltage silicone rubber insulation cable accessories is the damage on electrical treeing, initiated by partial discharges. The electrical treeing starts at unavoidable imperfections inside the material or at interfaces. The damage is usually irreversible and leads around the starting points to a partial destruction of the material. To prolong the lifetime and thereby to increase the assurance of the structural component commonly, for mechanical improvement constituted filler is modified to obtain a self-healing silicone rubber. Damage mechanism is analysed to address the filler to the damage mode. T2 - DGP-Frühjahrstagung und EPS-CMD27 CY - Berlin, Germany DA - 11.03.2018 KW - Self-healing silicone rubber KW - HV cable accessories PY - 2018 AN - OPUS4-45333 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ciornii, Dmitri A1 - Knigge, Xenia A1 - Radnik, Jörg A1 - Thünemann, Andreas A1 - Hodoroaba, Vasile-Dan A1 - Altmann, Korinna T1 - Identification of toxicologically relevant functional groups on micro- and nanoplastic particles’ surface by means of X-Ray photoelectron spectroscopy N2 - Microplastic and nanoplastic particles (MNP) are spread all over the world in various types, shapes and sizes making it very challenging to accurately analyse them. Each sampling procedure, sample preparation method and detection technique needs suitable reference materials to validate the method for accurate results. Furthermore, the effects of these MNPs should be evaluated by risk and hazard assessment with test particles close to reality. To better understand MNP behavior and aid in clarification of their interactions with organisms, we produced several MNP materials by top-down procedure and characterized their properties. Since surface properties mostly determine particles’ toxicity, the aim of the present study was to determine which functional groups are present on MNPs and how the surface can be affected by the production process and particle’s environment. T2 - SETAC 34th Meeting CY - Seville, Spain DA - 05.05.2024 KW - Microplastics KW - Nanoplastics KW - Polypropylene KW - XPS KW - SEM PY - 2024 AN - OPUS4-60037 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Hallier, Dorothea C. A1 - Smales, Glen Jacob A1 - Seitz, H. T1 - Extending Bio-SAXS measurements of Single-Stranded DNA-Binding Proteins: Radiation Protection of G5P by Cosolutes N2 - Small-angle X-ray scattering (SAXS) can be used for structural de- termination of biological macromolecules and polymers in their na- tive states. To improve the reliability of such experiments, the re- duction of radiation damage occurring from exposure to X-rays is needed.One method, is the use of scavenger molecules that protect macromolecules against radicals produced by radiation exposure.In this study we investigate the feasibility to apply the compatible solute, osmolyte and radiation protector Ectoine (THP(B)) as a scavenger throughout SAXS measurements of single-stranded DNA-binding protein Gene-V Protein (G5P/GVP). Therefore we monitor the radiation induced changes of G5P during bio-SAXS. The resulting microscopic energy-damage relation was determined by particle scattering simu- lations with TOPAS/Geant4. The results are interpreted in terms of radical scavenging as well as post-irradiation effects, related to preferential-exclusion from the protein surface. Thus, Ectoine provides an non-disturbing way to improve structure-determination of proteins via bio-SAXS in future studies. T2 - MultiChem Conference 2023 CY - Prague, Czech Republic DA - 26.04.2023 KW - Bio-SAXS KW - BioSAXS KW - Compatible solute KW - Cosolute KW - DNA KW - Dosimetry KW - Ectoin KW - Ectoine KW - Ectoin KW - G5P KW - GVP KW - Geant4 KW - Geant4-DNA KW - Gene five protein KW - Hydroxyectoine KW - Ionizing radiation damage KW - LEE KW - McSAS3 KW - Microdosimetry KW - Monte-Carlo simulations KW - OH Radical KW - OH radical scavenger KW - Osmolyte KW - Particle scattering simulations KW - Protein KW - Protein unfolding KW - Proteins KW - ROS KW - Radiation damage KW - Radical Scavenger KW - Radical scavenger KW - SAXS KW - Single-stranded DNA-binding proteins KW - Small-angle xray scattering KW - Topas KW - Topas-MC KW - Topas-nBio KW - X-ray scattering KW - ssDNA KW - Median lethal energy deposit PY - 2023 AN - OPUS4-57407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heilmann, Maria A1 - Prinz, Carsten A1 - Bienert, Ralf A1 - Wendt, Robert A1 - Kunkel, Benny A1 - Radnik, Jörg A1 - Hoell, Armin A1 - Wohlrab, Sebastian A1 - de Oliveira Guilherme Buzanich, Ana A1 - Emmerling, Franziska T1 - Size-Tunable Ni-Cu Core-Shell Nanoparticles: Structure, Composition, and Catalytic Activity N2 - Nanoparticles (NPs) have become important materials for a variety of chemical technologies, including catalysis. One of the main challenges is the reduction of green house gases, such as CO2. One opportunity besides the capturing is the conversion to synthesis gas via the reverse water-gas shift reaction. A facile and efficient method is described for the solvothermal synthesis of size-tunable, stable, and uniform NiCu core-shell NPs. The diameter of the NPs can be tuned in a range from 6 nm to 30 nm and the Ni:Cu ratio from 30:1 to 1:1. The NPs are structurally characterized with combination of transmission electron microscopy, anomalous small-angle X-ray scattering, X-ray photoelectron spectroscopy, and X-ray absorption fine structure. Using these analytical methods, a core-shell-shell structure their chemical composition is elucidated. A depletion from the core to the shell is observed, with the core consisting of NiCu alloy, surrounded by an inner Ni-rich shell and an outer NiO shell. The SiO2-supported NiCu core-shell NPs show pronounced selectivity of >99% for CO in the catalytic reduction of CO2 to CO using hydrogen as reactant (reverse water–gas shift reaction). T2 - Nanoalloys: recent developments and future perspectives Faraday Discussion CY - London, UK DA - 21.09.2022 KW - Nanoparticles KW - Core-shell KW - Catalysis PY - 2022 AN - OPUS4-56831 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maurer, G. A1 - Tuma, Dirk A1 - Chobanov, K. A1 - Kumełan, J. A1 - Pérez-Salado Kamps, Á. T1 - Gas solubility in ionic liquids: Solubility of a binary gas mixture in a pure ionic liquid as well as of a single gas in a binary liquid mixture N2 - Ionic Liquids (ILs) are employed in various fields, for example, reaction engineering (reactions with gases, such as hydroformylation (CO, H2), hydrogenation (H2), oxidation (O2)) or separation technology (separations of gases, reactants, and high-volatility reaction products). For the basic engineering of such processes, knowledge of phase equilibria, particularly of mixtures, over a broad (p,T) range is mandatory. This contribution reports on recent experimental results from our laboratory: – for the simultaneous solubility of a binary gas mixture in a pure ionic liquid – for the solubility of a single gas in a binary liquid solvent mixture. T2 - EUCHEM 2012 Conference on Molten Salts and Ionic Liquids CY - Celtic Manor, Wales, United Kingdom DA - 05.08.2012 KW - ionic liquids KW - gas solubility KW - Henry's constant PY - 2012 AN - OPUS4-35947 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kalies, G. A1 - Rockmann, R. A1 - Tuma, Dirk A1 - Arnrich, S. A1 - Bräuer, P. T1 - Reliable information on solids from liquid-Phase adsorption N2 - For the characterization of disperse and porous solids, usually single gas adsorption(GA) is employed. In the case of liquid adsorption (LA), the extraction of information on solids immediately becomes a more sophisticated matter since information on geometric as well energetic parameters of the solids is both superposed by liquid-mixture effects and displayed in excess terms. We have to ask if reliable solid parameters can be also obtained from LA isotherms. The enlarged data bank of gas and liquid adsorption measurements enables us to change systematically solid parameters (e.g., the pore width of MCM-41, the pore entrances of SBA-16, chemical heterogeneity) and to study in this way the influence of solid parameters on LA. T2 - The FOA 10, 10th International Conference on Fundamentals of Adsorption CY - Awaji Island, Japan DA - 23.05.2010 KW - porous solids KW - gas adsorption KW - excess isotherms PY - 2010 AN - OPUS4-35945 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Temperature in micromagnetism: Cell size and scaling effects of the stochastic Landau-Lifshitz equation N2 - The movement of the macroscopic magnetic moment in ferromagnetic systems can be described by the Landau-Lifshitz (LL) or Landau-Lifshitz-Gilbert (LLG) equation. These equations are strictly valid only at absolute zero temperature. To include temperature effects a stochastic version of the LL or LLG equation for a spin density of one per unit cell can be used instead. To apply the stochastic LL to micromagnetic simulations, where the spin density per unit cell is generally higher, a conversion regarding simulation cell size and temperature has to be established. Based on energetic considerations, a conversion for ferromagnetic bulk and thin film systems is proposed. The conversion is tested in micromagnetic simulations which are performed with the Object Oriented Micromagnetic Framework (OOMMF). The Curie temperatures of bulk Nickel, Cobalt and Iron systems as well as Nickel thin-film systems with thicknesses between 6.3 mono layer (ML) and 31ML are determined from micromagnetic simulations. The results show a good agreement with experimentally determined Curie temperatures of bulk and thin film systems when temperature scaling is performed according to the presented model. T2 - EUROMAT 2019 CY - Stockholm, Sweden DA - 01.09.2019 KW - Magnetic nanoparticles KW - Stochastic Landau Lifshitz Gilbert equation KW - Magnetic moment KW - Landau Lifshitz equation KW - Exchange interaction KW - OOMMF KW - Object oriented micromagnetic framework KW - Temeprature scaling KW - LLG KW - Ferromagnetism KW - Micromagnetism PY - 2019 AN - OPUS4-48762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Zutta Villate, J. M. T1 - Radioactive gold nanoparticles for cancer treatment: Size and cluster dependent damage studied by Geant4 Monte-Carlo simulations N2 - Dose enhancement by gold nanoparticles (AuNP) was shown to increase the biological effectiveness of radiation damage in biomolecules and tissue. Most of the current studies focus on external beam therapy on combination with AuNP. Here we present a Monte-Carlo study (Geant4) to characterise radioactive AuNP. Radioactive ¹⁹⁸Au emits beta and gamma rays and is considered for applications with solid tumours. To effectively apply ¹⁹⁸AuNP their energy deposit characteristics have to be determined in terms of intrinsic and extrinsic properties e.g. AuNP diameter, AuNP density, and their clustering behaviour. After each decay process, the energy deposit, inelastic scattering events, kinetic energy spectrum of secondary particles within the AuNP themselves and in a spherical target volume of water up to 1 μm radius were determined. Simulations were performed for AuNP radii ranging from 2.5 nm to 20 nm radius, different cluster sizes and densities. The results show an increase of the energy deposit in the vicinity of the AuNP up to 150 nm. This effect nearly vanishes for distances up to one micron. For the case of AuNP clusters and the same activity, the enhancement of the energy deposit increases with the relative gold mass percentage and therefore can be adjusted by changing AuNP radius or clustering behaviour. T2 - EUROMAT 2019 CY - Stockholm, Sweden DA - 01.09.2019 KW - DNA KW - Dosimetry KW - Microdosimetry KW - Geant4 KW - MCS KW - Nanoparticle KW - AuNP KW - Gold Nanoparticle KW - low energy electrons KW - LEE KW - OH radicals KW - particle scattering KW - Radiationtherapy KW - Radioactive decay KW - Monte-Carlo simulation KW - Energy deposit KW - DNA damage PY - 2019 AN - OPUS4-48763 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan A1 - Pellegrino, F. A1 - Maurino, V. T1 - Morpho-Chemical Characterisation of Me-TiO2 Nanoparticles for Enhanced Photocatalytical Activity N2 - The conversion of solar energy into electricity and solar fuels is of crucial importance for a green and sustainable future. Water splitting using semiconductor photo-catalysts is considered a sustainable method to produce clean hydrogen (H2) fuel. Nevertheless, H2 photo-production efficiency remains still low, although extensive research works to understand better the mechanisms of the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) are being carried out. In this respect, TiO2 is a key photoactive material, usually employed with a co-catalyst deposited onto the surface to enhance charge carriers’ separation and catalyze surface charge transfer reactions. The deposition of a co-catalyst on the TiO2 nanoparticle surface represents one successful way to enhance the activity of the photocatalyst through a modification of its surface and redox properties. In this context, high-resolution scanning electron microscopy coupled with elemental analysis by energy-dispersive X-ray spectroscopy (EDS) is fundamental for studying and understanding the effect of the nanoparticle morphology on the functional properties of shape-controlled TiO2 crystals (bipyramides, platelets, and elongated particles). Different types of metal-semiconductor combinations, TiO2 shapes and dopant metals (Ag, Pt, etc) and metal concentrations will be discussed. T2 - ECASIA 2022 CY - Limerick, Ireland DA - 29.05.2022 KW - Titania nanoparticles KW - Photocatalysis KW - Scanning electron microscopy KW - Energy dispersive X-ray spectroscopy PY - 2022 AN - OPUS4-54977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habibimarkani, Heydar A1 - John, Elisabeth A1 - Schusterbauer, Robert A1 - Abram, Sarah-Luise A1 - Prinz, Carsten A1 - Resch-Genger, Ute A1 - Hodoroaba, Vasile-Dan A1 - Radnik, Jörg T1 - Investigating the Synergistic Effects of FeNi-Oxide Nanoparticles as Water Electrolysis Catalysts: A Multi-Technique Characterization Approach N2 - Electrocatalysis is and will continue to play a central role in the development of a new and modern sustainable economy, especially for chemicals and fuels. The storage of excess electrical energy into chemical energy by splitting water into hydrogen and oxygen is a feasible solution in this economic sector. A major drawback of electrical energy lies in the storage. Therefore, hydrogen is discussed as promising alternative. Fortunately, this issue can be effectively addressed through the implementation of chemical storage mechanisms. Due to their abundance on Earth and inherent stability in alkaline solutions, transition-metal oxides have become one of several viable alternatives to conventional noble-metal catalysts. Since FeNi oxide is one of the most active oxygen evolution reaction (OER) electrocatalysts for alkaline water electrolysis, it has been the subject of extensive research. A series of different types of FeNi oxide nanoparticles (NPs) with atomic ratios covering a broad range, and various sizes with specific stoichiometric and non-stoichiometric iron and nickel ratios was synthesized and characterized by the combination of surface analysis techniques, such as time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). The morphology was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which revealed the coexistence of mixed and unmixed iron and nickel NPs with comparable sizes in the range of 30–40 nm across all ratios. The synthesis technique displayed control over the iron-nickel ratio, as evidenced by energy dispersive X-ray spectroscopy (EDS) data. The presence of magnetite (Fe3O4) was detected in all samples investigated by X-ray diffraction (XRD). Furthermore, the existence of nickel ferrite (NiFe2O4) was shown in the Fe2Ni by XRD analysis. For the cyclic voltammetry (CV) measurements, the NPs were deposited onto glassy carbon electrodes using Nafion® as an ionomer, and 1 M KOH was employed as the electrolyte. Subsequently, the NPs/Nafion® electrode was transferred into the ToF-SIMS chamber to allow surface analysis and depth profiling. The ToF-SIMS analysis revealed distinct peaks corresponding to Fe, Ni, and other peaks associated with Nafion®, whereas a straightforward correlation between the Ni.Fe ratio and the SIMS peak pattern is not possible. The catalytic activity towards OER was evaluated through CV measurements, where the Fe2Ni3 ratio exhibited the most favorable performance, displaying a lower overpotential. T2 - European Materials Research Society (E-MRS) Fall 2023 CY - Warsaw, Poland DA - 18.09.2023 KW - FeNi-Oxide NPs KW - ToF-SIMS KW - Catalysts KW - OER PY - 2023 AN - OPUS4-59139 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habibimarkani, Heydar A1 - John, Elisabeth A1 - Schusterbauer, Robert A1 - Abram, Sarah-Luise A1 - Prinz, Carsten A1 - Resch-Genger, Ute A1 - Hodoroaba, Vasile-Dan A1 - Radnik, Jörg T1 - Complementary Characterization of FeNi-Oxide Nanoparticles as Catalysts for Water Electrolysis combining Electron Microscopy, EDS, XRD, ToF-SIMS and Electrochemical Analysis N2 - Electrocatalysis is and will continue to play a central role in the development of a new and modern sustainable economy, especially for chemicals and fuels. The storage of excess electrical energy into chemical energy by splitting water into hydrogen and oxygen is a feasible solution in this economic sector. A major drawback of electrical energy lies in the storage. Therefore, hydrogen is discussed as promising alternative. Fortunately, this issue can be effectively addressed through the implementation of chemical storage mechanisms. Due to their abundance on Earth and inherent stability in alkaline solutions, transition-metal oxides have become one of several viable alternatives to conventional noble-metal catalysts. Since FeNi oxide is one of the most active oxygen evolution reaction (OER) electrocatalysts for alkaline water electrolysis, it has been the subject of extensive research. A series of different types of FeNi oxide nanoparticles (NPs) with atomic ratios covering a broad range, and various sizes with specific stoichiometric and non-stoichiometric iron and nickel ratios was synthesized and characterized by the combination of surface analysis techniques, such as time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). The morphology was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which revealed the coexistence of mixed and unmixed iron and nickel NPs with comparable sizes in the range of 30–40 nm across all ratios. The synthesis technique displayed control over the iron-nickel ratio, as evidenced by energy dispersive X-ray spectroscopy (EDS) data. The presence of magnetite (Fe3O4) was detected in all samples investigated by X-ray diffraction (XRD). Furthermore, the existence of nickel ferrite (NiFe2O4) was shown in the Fe2Ni by XRD analysis. For the cyclic voltammetry (CV) measurements, the NPs were deposited onto glassy carbon electrodes using Nafion® as an ionomer, and 1 M KOH was employed as the electrolyte. Subsequently, the NPs/Nafion® electrode was transferred into the ToF-SIMS chamber to allow surface analysis and depth profiling. The ToF-SIMS analysis revealed distinct peaks corresponding to Fe, Ni, and other peaks associated with Nafion®, whereas a straightforward correlation between the Ni.Fe ratio and the SIMS peak pattern is not possible. The catalytic activity towards OER was evaluated through CV measurements, where the Fe2Ni3 ratio exhibited the most favorable performance, displaying a lower overpotential. T2 - SIMS Europe 2023 CY - Nottingham, England DA - 02.09.2023 KW - FeNi-Oxide NPs KW - ToF-SIMS KW - Catalysts KW - OER PY - 2023 AN - OPUS4-59143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winckelmann, Alexander A1 - Abad Andrade, Carlos Enrique A1 - Richter, Silke A1 - Recknagel, Sebastian A1 - Riedel, Jens A1 - Vogel, Jochen A1 - Panne, Ulrich T1 - Next level lithium isotope analysis by atomic absorption spectrometry in combination with machine learning N2 - An alternative method for lithium isotope amount ratio analysis is proposed by combining atomic absorption spectrometry with spectra data analysis by machine leaning. It is based on the well-known isotope shift of around 15 pm for the electronic transition at wavelength 670.7845 nm which can be measured by a high-resolution continuum source atomic absorption spectrometer (HR-CS-AAS). For isotope amount ratio analysis, a scalable three boosting machine learning algorithm (XGBoost) was employed and calibrated with a set of samples with a 6Li isotope amount fraction ranging from 99% to 6%. The absolute Li isotope amount fractions of these calibration samples were previously measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) and used as ab-initio data for the machine learning algorithm. Validation of the machine leaning model was performed with two standard reference materials (LSVEC and IRMM-016). The procedure was employed for the isotope amount ratio determination of a set of stock chemicals (Li2CO3, LiNO3, LiCl, LiOH, and LiF) as well as a BAM candidate LiMNC cathode reference material. Achieved uncertainties are one order of magnitude higher than those obtained by MC-ICP-MS. This precision and accuracy is nonetheless sufficient to resolve natural occurring variations in Lithium isotope ratios. Also, the LiMNC material was analyzed by HR-CS-AAS with and without matrix purification. The results are comparable within statistical error. T2 - Make and Measure 2020 CY - Online Meeting DA - 15.10.2020 KW - Lithium batteries KW - HR-CS-AAS KW - Machine learning KW - Isotope analysis KW - Spectrometry PY - 2020 AN - OPUS4-51541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chemello, Giovanni A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan T1 - Towards Reproducible Analysis Workflows for Reliable Structural and Chemical Composition of Industrial Graphene N2 - The scientific and technological interest in graphene has been growing more and more in the late years due to its outstanding properties and diverse promising applications. However, graphene implementation into the industrial market is still limited and many challenges are yet to be addressed before this material can become suitable for the large-scale production. One of the most crucial challenge to overcome is to develop reliable and reproducible ways to characterize the material properties which can heavily affect the product performance. In our study the chemical composition of nine different samples of industrial graphene, graphene oxide and functionalized graphene were investigated. The samples were analysed both in form of powder and pellets. A comparative characterisation of the chemical composition was performed through X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Spectroscopy (EDX). XPS depth resolution is in the order of 10 nm, while for EDX the analysis was performed at two different energy levels, i.e. 5 keV and 15 keV, and thus varying the analysis depth from 200 nm to 2000 nm. The XPS measurement area is 300x700 µm² while the EDX measurement was performed by analysing a grid of 25 locations (5x5) of 150 x 150 ?m2 area, covering the whole pellet surface of 5 mm diameter and then calculating the mean of the elemental concentration. The results of the elemental concentration values from XPS and EDX analyses show a good agreement for all the elements presents in the samples, despite the different spatial resolutions of the two techniques. Therefore, the samples appear homogeneous both in the lateral and vertical directions. The results relative to powder and pellets samples do not differ in a significant way except for a slight increase in the carbon content regarding the pellet samples, probably due to a minor contamination effect introduced through pressing. Nevertheless, pellets samples appear to be quite representative for the material while being much more convenient in terms of handling and safety compared to nano-powders and providing a regular flat surface for EDX analysis. Finally, this approach correlating XPS and EDS represents a simple, fast and reliable way for characterizing the chemical composition and the homogeneity of industrial graphene. This study is part of the project Standardisation of structural and chemical properties of graphene (ISO-G-SCoPe) which has received funding from the EMPIR programme co-financed by the Participating States and from the European Union?s Horizon 2020 research and innovation programme under Grant agreement No. 19NRM04. T2 - SALSA Make and Measure... and Machines CY - Online meeting DA - 16.09.2021 KW - Graphene KW - XPS KW - EDX KW - Graphene functionalisation PY - 2021 UR - https://fakultaeten.hu-berlin.de/en/mnf/forschung_internationales/grs/salsa/SALSA_MM AN - OPUS4-53463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chemello, Giovanni A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan T1 - Correlative analysis through XPS and EDX measurements for accurate chemical composition of industrial Graphene N2 - The scientific and technological interest in graphene has been growing more and more in the late years due to its outstanding properties and diverse promising applications. However, graphene implementation into the industrial market is still limited and many challenges are yet to be addressed before this material can become suitable for the large-scale production. One of the most crucial challenge to overcome is to develop reliable and reproducible ways to characterize the material properties which can heavily affect the product performance. In our study the chemical composition of nine different samples of industrial graphene, graphene oxide and functionalized graphene were investigated. The samples were analysed both in form of powder and pellets. A comparative characterisation of the chemical composition was performed through X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Spectroscopy (EDX). XPS depth resolution is in the order of 10 nm, while for EDX the analysis was performed at two different energy levels, i.e. 5 keV and 15 keV, and thus varying the analysis depth from 200 nm to 2000 nm. The XPS measurement area is 300x700 µm² while the EDX measurement was performed by analysing a grid of 25 locations (5x5) of 150 x 150 ?m2 area, covering the whole pellet surface of 5 mm diameter and then calculating the mean of the elemental concentration. The results of the elemental concentration values from XPS and EDX analyses show a good agreement for all the elements presents in the samples, despite the different spatial resolutions of the two techniques. Therefore, the samples appear homogeneous both in the lateral and vertical directions. The results relative to powder and pellets samples do not differ in a significant way except for a slight increase in the carbon content regarding the pellet samples, probably due to a minor contamination effect introduced through pressing. Nevertheless, pellets samples appear to be quite representative for the material while being much more convenient in terms of handling and safety compared to nano-powders and providing a regular flat surface for EDX analysis. Finally, this approach correlating XPS and EDS represents a simple, fast and reliable way for characterizing the chemical composition and the homogeneity of industrial graphene. This study is part of the project ?Standardisation of structural and chemical properties of graphene? (ISO-G-SCoPe) which has received funding from the EMPIR programme co-financed by the Participating States and from the European Union?s Horizon 2020 research and innovation programme under Grant agreement No. 19NRM04. T2 - 2021 Fall Meeting of the European Materials Research Society (E-MRS) CY - Online meeting DA - 20.9.2021 KW - Graphene KW - XPS KW - EDS KW - Standardisation KW - Graphene functionalization PY - 2021 UR - https://www.european-mrs.com/meetings/2021-fall-meeting AN - OPUS4-53462 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Zutta Villate, J. M. T1 - BP150: Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement by Monte-Carlo based particle scattering Simulations N2 - Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined. Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. We apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. T2 - DPG Frühjahrstagung CY - Dresden, Germany DA - 26.03.2023 KW - AuNP KW - Beta decay KW - Brachytherapy KW - Cancer treatment KW - Clustered nanoparticles KW - DNA KW - DNA damage KW - Dosimetry KW - Energy deposit KW - Geant4 KW - Geant4-DNA KW - Gold Nanoparticles KW - LEE KW - Livermore model KW - Low energy electrons KW - MCS KW - Microdosimetry KW - Monte-Carlo simulation KW - NP KW - OH radical KW - Penelope model KW - Radiation damage KW - Radiation therapy KW - Radiationtherapy KW - Radioactive decay KW - Radiolysis KW - Radiotherapy KW - Simulation KW - TOPAS KW - TOPAS-nbio KW - Beta particle KW - Particle scattering KW - Protein KW - Proteins PY - 2023 AN - OPUS4-57253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement by Monte-Carlo based particle scattering Simulations N2 - Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined.[1] Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. To estimate these effects, particle scattering simulations are applied. In general, different approaches for modeling the AuNP and their distribution within the cell are possible. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. [2] These models are applicable to simulations of internal emitters and external radiation sources. Most of the current studies on AuNP focus on external beam therapy. In contrast, we apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. These results are the foundation for ongoing experimental work which aims to obtain a mechanistic understanding of cell death induced by radioactive 198Au. T2 - #RSCposter 2023 CY - Online meeting DA - 28.02.2023 KW - AuNP KW - Beta decay KW - Brachytherapy KW - Cancer treatment KW - Clustered nanoparticles KW - DNA KW - DNA damage KW - Dosimetry KW - Energy deposit KW - Geant4 KW - Geant4-DNA KW - Gold Nanoparticles KW - LEE KW - Livermore model KW - Low energy electrons KW - MCS KW - Microdosimetry KW - Monte-Carlo simulation KW - NP KW - OH radical KW - Penelope model KW - Radiation damage KW - Radiation therapy KW - Radiationtherapy KW - Radiotherapy KW - Radioactive decay KW - Radiolysis KW - Simulation KW - TOPAS KW - TOPAS-nbio KW - beta particle KW - particle scattering PY - 2023 AN - OPUS4-57060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Temperature in micromagnetism: Cell size and scaling effects of the stochastic Landau-Lifshitz equation N2 - The movement of the macroscopic magnetic moment in ferromagnetic systems can be described by the Landau-Lifshitz (LL) or Landau-Lifshitz-Gilbert (LLG) equation. These equations are strictly valid only at absolute zero temperature. To include temperature effects a stochastic version of the LL or LLG equation for a spin density of one per unit cell can be used instead. To apply the stochastic LL to micromagnetic simulations, where the spin density per unit cell is generally higher, a conversion regarding simulation cell size and temperature has to be established. Based on energetic considerations, a conversion for ferromagnetic bulk and thin film systems is proposed. The conversion is tested in micromagnetic simulations which are performed with the Object Oriented Micromagnetic Framework (OOMMF). The Curie temperatures of bulk Nickel, Cobalt and Iron systems as well as Nickel thin-film systems with thicknesses between 6.3 mono layer (ML) and 31ML are determined from micromagnetic simulations. The results show a good agreement with experimentally determined Curie temperatures of bulk and thin film systems when temperature scaling is performed according to the presented model. T2 - #RSCposter 2023 CY - Online meeting DA - 28.02.2023 KW - Exchange interaction KW - Ferromagnetism KW - LLG KW - Landau Lifshitz equation KW - Magnetic moment KW - Magnetic nanoparticles KW - Micromagnetism KW - OOMMF KW - Object oriented micromagnetic framework KW - Stochastic Landau Lifshitz Gilbert equation KW - Temperature scaling PY - 2023 AN - OPUS4-57062 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David A1 - Häusler, I. A1 - Knigge, Xenia A1 - Hodoroaba, Vasile-Dan A1 - Emmerling, Franziska A1 - Reiss, P. A1 - Resch-Genger, Ute T1 - One-Pot Heat-Up Synthesis of ZnSe Magic-Sized Clusters Using Thiol Ligands N2 - The unique optoelectronic properties of semiconductor nanocrystals, also termed quantum dots (QDs), have led to many advances in optoelectronic devices, bioimaging, and biosensing. This strong potential in a wide range of applications sparked the interest for a better understanding of the QD formation mechanisms. Recent studies have shown that atomically defined, zero-dimensional magic-size clusters (MSCs) play a crucial role during the nucleation and growth of QDs. Thereby MSCs consist of discrete numbers of ions leading to narrow size distributions and thus narrow absorption peaks, which evolve in discrete steps from one stable size to the next. The formation of MSCs was found in the synthesis of II-VI and III-V QDs but only limited synthesis approaches are available for the synthesis of MSCs in single-ensemble form without coexistence of other-size QDs. These MSCs can further self-assemble into two- and three-dimensional hybrid structures using organic ligands like diamines, leading to enhanced photoluminescence properties and catalytic activities. In this contribution, we present a synthesis strategy for the preparation of single-sized ZnSe MSCs. With a band gap of 2.7 eV and being an earth-abundant material, ZnSe QDs are interesting for light-emitting devices, blue-green lasers, photocatalysis, and fluorescence probes. In contrast to other studies, our approach is based on a one-pot heat-up synthesis and uses less toxic and dangerous zinc precursors (e.g. zinc stearate). Knowing that thiol-based ligands can alter the formation process of ZnSe QDs, we investigated the influence of 1-dodecanethiol on the ZnSe MSC formation using absorption spectroscopy, TEM, XPS, and XRD. By variation of the thiol ligand concentration and reaction temperature, we were able to synthesize two new ZnSe MSC sizes, the largest so far, by using easy-to-handle precursors. T2 - NANOHYBRID - Hamburg Conference on Complex Nanostructures CY - Hamburg, Germany DA - 04.10.2022 KW - ZnSe KW - Magic-sized cluster KW - Nanoparticle KW - Synthesis KW - Nanomaterial PY - 2022 AN - OPUS4-56193 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maurer, G. A1 - Tuma, Dirk A1 - Chobanov, K. A1 - Kumełan, J. A1 - Pérez-Salado Kamps, Á. T1 - High-pressure gas solubility in mixtures with one compound being an „alternative“ solvent N2 - The term „Alternative Solvents“ often refers to ionic liquids (ILs), mainly to distinguish these substances from traditional (i.e., molecular) solvents. In applications, any „alternative“ is required to perform better than something that is proven and tested. To bring ILs into practical use, availability and costs are the fundamental points to be addressed. There are two ways to proceed: ▬ tailoring a molecule, implanting the expected characteristics advantage: optimization of the targeted performance possible risks: outcome not always foreseeable, costly and time-intensive (“trial and error“) ▬ to target on mixtures of well-characterized ILs with molecular solvents advantage: substance characteristics are known, less costly, less time-consuming, mixture composition another tunable parameter risks: the same but with less impact For the basic engineering of technical processes, knowledge of phase equilibria, particularly of mixtures, over a broad (p,T) range is mandatory. This contribution reports on recent experimental results from our laboratory: ▬ the solubility of CO2 in a mixture of water and [bmim][CH3SO4] ▬ the solubility of CO2 in a mixture of methanol and [bmim][PF6] T2 - EUCHEM 2014 5th Conference on Molten Salts and Ionic Liquids CY - Tallinn, Estonia DA - 06.07.2014 KW - Ionic liquids KW - Gas solubility KW - Henry's constant PY - 2014 AN - OPUS4-35944 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Zutta Villate, J. M. T1 - Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement by Monte-Carlo based particle scattering Simulations N2 - Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined.[1] Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. To estimate these effects, particle scattering simulations are applied. In general, different approaches for modeling the AuNP and their distribution within the cell are possible. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. [2] These models are applicable to simulations of internal emitters and external radiation sources. Most of the current studies on AuNP focus on external beam therapy. In contrast, we apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. These results are the foundation for ongoing experimental work which aims to obtain a mechanistic understanding of cell death induced by radioactive 198Au. T2 - NALS 2022 CY - Santander, Spain DA - 27.04.2022 KW - AuNP KW - Beta decay KW - beta particle KW - Brachytherapy KW - Cancer treatment KW - Clustered nanoparticles KW - DNA KW - DNA damage KW - Dosimetry KW - Energy deposit KW - Geant4 KW - Geant4-DNA KW - Gold Nanoparticles KW - LEE KW - Livermore model KW - Low energy electrons KW - MCS KW - Microdosimetry KW - Monte-Carlo simulation KW - NP KW - OH radical KW - particle scattering KW - Penelope model KW - Radiation damage KW - Radiation therapy KW - Radiationtherapy KW - Radioactive decay KW - Radiolysis KW - Simulation KW - TOPAS KW - TOPAS-nbio PY - 2022 AN - OPUS4-54775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Giovannozzi, A. A1 - Rossi, A. A1 - Kovac, J. A1 - Ekar, J. A1 - Goenaga-Infante, H. A1 - Clarkson, C. A1 - Clifford, C. A1 - Cant, D. A1 - Minelli, C. A1 - Reithofer, M. A1 - Lindner, G. A1 - Venzago, C. A1 - Bohmer, N. A1 - Drexler, C.-P. A1 - Schedler, U. A1 - Thiele, T. A1 - Lechart, F. A1 - Kästner, B. A1 - Sjövall, P. A1 - Johnston, L. A1 - Tan, Gunnar A1 - Radnik, Jörg T1 - Standardised Measurements of Surface Functionalities on Nanoparticles N2 - Engineered nanoparticles (NPs) with various chemical compositions and surface functionalities are routinely fabricated for industrial applications such as medical diagnostics, drug delivery, sensing, catalysis, energy conversion and storage, opto-electronics, and information storage which improve the quality of life and European prosperity. NP function, performance, interaction with biological species, and environmental fate are largely determined by their surface functionalities. Standardized repeatable surface characterization methods are therefore vital for quality control of NPs, and to meet increasing concerns regarding their safety. Therefore, industry, regulatory agencies, and policymakers need validated traceable measurement methods and reference materials. This calls for fit-for-purpose, validated, and standardized methods, and reference data and materials on the surface chemistry of engineered NPs. Here, we present a concept for the development of such standardized measurement protocols utilizing method cross-validation and interlaboratory comparisons (ILCs) with emphasis on both advanced measurement methods such as quantitative Nuclear Magnetic Resonance (qNMR), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) and cost-efficient, non-surface specific methods like optical assays and electrochemical titration methods. T2 - European Partnership on Metrology 2023 Review Conference CY - Amsterdam, Netherlands DA - 07.11.2023 KW - Surface chemistry KW - Quality assurance KW - Traceability PY - 2023 AN - OPUS4-59142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Carstensen, Niels A1 - Schirdewahn, S. A1 - Merklein, M. A1 - Hilgenberg, Kai T1 - Generation of Tribosystems by Additive Surface Treatment on Tool Steel Substrate N2 - Laser implantation aims at reducing friction and wear on highly stressed surfaces in forming processes. Especially the hot stamping process that is used as a resource efficient process for manufacturing geometrical complex and high-strength structures, exhibits severe wear and high friction during the forming operation. The laser implantation process addresses this problem by combining two different approaches (surface modification and surface structuring) in surface technology by creating elevated, highly wear-resistant micro-features to influence the tribological performance. Pure TiB2 implants have shown to reduce tool-sided wear significally and improve the part formability by reducing local necking in deep drawing tests. Within the scope of this work, TiB2-TiC and TiB2-TaC hard material mixtures are implanted on X38CrMoV5-3 hot work tool steel. The aim is to investigate how the implant material properties can be influenced by the application of different mixing ratios of hard material mixtures under the specific variation of the process parameters. Distinct implant formations are tested on a novel test apparatus to examine the influence on the tribological properties. From the analyses of the implant properties by hardness measurements, light microscopic images, EDX and XRD analyses process parameter ranges are identified to produce defect-free dome- and ring-shaped implants. The specific process parameters (pulse power, pulse duration, mixing ratio and coating thickness) can be used for the determination of the implant geometry (height, width and depth). The tribological tests exhibit improved friction and wear properties. Based on these results, a tribosystem manufactured by this additive surface treatment technology shows great potential to enhance the effectiveness of the hot stamping process. T2 - Friction 2021 CY - Sankt Augustin, Germany DA - 18.11.2021 KW - Laser implantation KW - Surface modification KW - Additive surface treatment KW - Hot stamping KW - Tool steel PY - 2021 AN - OPUS4-53809 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Merz, Benjamin A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Position Detection for Hybrid Repair of gas turbine blades using PBF-LB/M N2 - This poster presents a workflow for camera-based position detection of components within PBF-LB/M machines. This enables a hybrid repair process of highly stressed components such as gas turbine blades using PBF-LB/M. T2 - Kuratoriumsführung CY - Berlin, Germany DA - 21.06.2022 KW - Additive Manufacturing KW - PBF-LB/M KW - Position detection KW - Camera KW - Image processing PY - 2022 AN - OPUS4-56587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schirdewahn, S. A1 - Spranger, Felix A1 - Hilgenberg, Kai A1 - Merklein, M. T1 - Tribological performance of localized dispersed X38CrMoV5-3 surfaces for hot stamping of Al-Si coated 22MnB5 sheets N2 - Over the last years, the weight of modern car bodies has risen significantly due to the increasing customers’ demand for comfort and safety equipment. However, this ongoing trend leads to an increasing fuel consumption and thus to higher carbon dioxide emissions. In order to counteract these problems, hot stamping has been established in the automotive industry as a key technology for lightweight construction, regarding the manufacturing of safety-relevant car body components. Hot stamped parts are commonly made out of boron-manganese steel 22MnB5, which is initially austenized and subsequently formed and quenched in one process step. As a result, geometrical complex structures with an ultimate tensile strength of 1500 MPa are generated. The surfaces of the workpieces are coated with an Al-Si layer to avoid oxide scale formation and to ensure corro-sion protection. However, the coating system leads to an increased adhesive wear on the tool sur-face due to the high thermo-mechanical tool stresses. Therefore, a time and cost consuming rework of the hot stamping tools is required. The aim of this study is to increase the tribological perfor-mance of hot stamping tools by using a laser implantation process. This technique allows the ma-nufacturing of separated, elevated and dome-shaped microstructures on the tool surface in conse-quence of a localized dispersing of hard ceramic particles by pulsed laser radiation. The generated surface features offer great potential for reducing the tribological load, due to their high hardness and wear resistance. For this purpose, the friction coefficient of unmodified and laser implanted tool surfaces were examined and compared by using a modified pin-on-disk test. In addition, the surfaces were analyzed by optical measurements in order to quantify the amount of wear. T2 - 7th International Conference on Hot Sheet Metal Forming of High-Performance Steel CHS2-2019 CY - Lulea, Sweden DA - 02.06.2019 KW - Laser implantation KW - Surface texturing KW - Hot stamping PY - 2019 AN - OPUS4-48323 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nazarzadehmoafi, Maryam A1 - Zscherpel, Uwe A1 - Altenburg, Simon A1 - Mohr, Gunther A1 - Maierhofer, Christiane A1 - Waske, Anja T1 - Detection of imprinted artificial defects in additively-manufactured samples by means of radiological inspections N2 - As a part of ProMoAM project, we are optimizing a prototype X-ray backscatter to reach NDT requirements, and thereafter to apply it for process monitoring. Moreover, we studied the capability of a radiography approach to detect artificial defects in AM components made by laser powder bed fusion (L-PBF). T2 - Workshop on Additive Manufacturing: Process, materials, simulation & implants CY - Berlin, Germany DA - 13.05.2019 KW - Additive manufacturing KW - NDT KW - Radiological inspections PY - 2019 AN - OPUS4-48515 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Merz, Benjamin A1 - Poka, Konstantin A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Precise Position Detection for Repair of Gas Turbine Blades using PBF-LB/M N2 - Additive manufacturing (AM) technologies are becoming increasingly important, not only for the manufacture of parts, but also as repair technology that complement existing production technologies. Powder bed fusion of metals by laser beam (PBF-LB/M) combines the freedom in design with high achievable accuracy, making it ideal as a repair approach. However, there are still challenges in adapting process for repair applications. When mounting parts inside PBF-LB/M machines, their real position within the build volume is unknown. One goal of a repair process is to minimize the offset between the base component and the additively manufactured structure to reduce additional rework. For a minimum offset between component and additively manufactured structure, the actual position of the component has to be identified with high precision within the machine coordinate system (MCS). In this work a process setup is presented that allows the actual position of a gas turbine blade to be detected inside a PBF-LB/M machine. A high resolution camera with 65 megapixel is used for this purpose. The presented setup is implemented on a SLM 280 HL PBF-LB/M machine. In addition to the setup, a novel repair workflow using PBF-LB/M is presented. The developed setup and workflow consider inaccuracies in the component and camera mounting, as well as process inaccuracies. This includes keystone distortion correction by homography. The machine setup and workflow are used to repair a real gas turbine blade. Subsequently the offset between the turbine blade and the additivley manufactured structure is validated by 3D scanning the repaired part. The maximum offset is 160 µm. The presented approach can be extended to other geometries and PBF-LB/M machine manufacturers. The high-resolution camera approach is platform independent, which facilates the market penetration of PBF-LB/M repair processes. T2 - International Symposium Additive Manufacturing 2023 (ISAM 2023) CY - Dresden, Germany DA - 30.11.2023 KW - additive manufacturing KW - powder bed fusion of metals utilizing a laser beam KW - PBF-LB/M KW - hybrid repair KW - position detection KW - high-resolution camera PY - 2023 AN - OPUS4-59193 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schneider, M. A1 - Schlingmann, T. A1 - Schmidt, J. A1 - Bettge, Dirk A1 - Hilgenberg, Kai A1 - Binder, M. A1 - Klöden, B. T1 - A Round Robin Test To Investigate The Printing Quality Of PBF LB/M Processed AlSi10Mg N2 - When it comes to higher accuracies, new technologies and real applications in additive manufacturing, there is one topic which cannot be avoided: The material response on the chosen processing parameters and its agreement and correspondence with literature data of the wrought material grade counterpart. In industrial Additive Manufacturing (AM) standards in terms of printing parameters, protection gas atmospheres or powder handling instructions are not obligatory. Therefore, the question must be answered whether the AM process is reproducible and reliable over different printing companies. This was the motivation to realize a round robin test between 8 European printing companies and academic partners. The consortium had printed and tested fatigue and tensile testing bars under plant-specific conditions. A commonly used cast aluminum alloy, AlSi10Mg, was chosen as test material for the PBF-LB/M process. Differences of the results between the partners and the scatter itself were discussed in detail. T2 - World PM2022 CY - Lyon, France DA - 09.10.2022 KW - Additive manufacturing KW - AlSi10Mg KW - Laser powder bed fusion KW - Round robin KW - Reproducibility PY - 2022 AN - OPUS4-56303 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Tiago A1 - Madia, Mauro A1 - Hilgenberg, Kai A1 - Gärtner, F. A1 - Klassen, T. T1 - Structural integrity of cold spray repaired aerospace components N2 - Components in aircrafts are usually replaced when critical defects are present. An alternative approach is repairing using gas dynamic cold spraying: metal particles are shot at a surface at supersonic speeds to selectively rebuild damaged material. Compared to other material-deposition techniques, its advantage is the small thermal impact on the component, preserving its mechanical properties. Component-repair can save considerable amounts of energy and resources. However, its industrial application at large scale needs reproducible, good repair-material properties to guarantee a safe component life. The aim of this project is the development of safe, automatized repair-procedures considering the mechanical fatigue properties of the repair. T2 - ICEAF VII Conference 2023 CY - Spetses, Greece DA - 21.06.2023 KW - Cold Spray KW - Repair KW - Fatigue KW - Fatigue Crack Growth KW - Slow Strain Rate Testing PY - 2023 AN - OPUS4-57784 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ulbricht, Alexander A1 - Altenburg, Simon A1 - Sprengel, Maximilian A1 - Sommer, Konstantin A1 - Mohr, Gunther A1 - Fritsch, Tobias A1 - Mishurova, Tatiana A1 - Serrano Munoz, Itziar A1 - Evans, Alexander A1 - Hofmann, Michael A1 - Bruno, Giovanni T1 - Separation of the Formation Mechanisms of Residual Stresses in LPBF 316L N2 - Rapid cooling rates and steep temperature gradients are characteristic of additively manufactured parts and important factors for the residual stress formation. This study examined the influence of heat accumulation on the distribution of residual stress in two prisms produced by Laser Powder Bed Fusion (LPBF) of austenitic stainless steel 316L. The layers of the prisms were exposed using two different border fill scan strategies: one scanned from the centre to the perimeter and the other from the perimeter to the centre. The goal was to reveal the effect of different heat inputs on samples featuring the same solidification shrinkage. Residual stress was characterised in one plane perpendicular to the building direction at the mid height using Neutron and Lab X-ray diffraction. Thermography data obtained during the build process were analysed in order to correlate the cooling rates and apparent surface temperatures with the residual stress results. Optical microscopy and micro computed tomography were used to correlate defect populations with the residual stress distribution. The two scanning strategies led to residual stress distributions that were typical for additively manufactured components: compressive stresses in the bulk and tensile stresses at the surface. However, due to the different heat accumulation, the maximum residual stress levels differed. We concluded that solidification shrinkage plays a major role in determining the shape of the residual stress distribution, while the temperature gradient mechanism appears to determine the magnitude of peak residual stresses. T2 - MLZ User Meeting 2020 CY - Online meeting DA - 08.12.2020 KW - Computed tomography KW - Neutron diffraction KW - X-ray diffraction KW - Additive manufacturing KW - Residual stress KW - Thermography KW - LPBF KW - Laser Powder Bed Fusion PY - 2020 AN - OPUS4-51793 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ulbricht, Alexander A1 - Altenburg, Simon A1 - Mohr, Gunther T1 - µCT as Benchmark for Online Process Monitoring N2 - µCT is used to validate the capability of online monitoring for in-situ detection of defects during the L-PBF build process, which is a focus of the TF project ProMoAM. Our first experiments show that online monitoring using thermography and optical tomography cameras are able to detect defects in the built part. But further research is needed to understand root cause of the correlation. T2 - Workshop on Additive Manufacturing: Process, materials, simulation & implants CY - BAM, Berlin, Germany DA - 13.05.2019 KW - Computed tomography KW - Online Process Monitoring KW - Additive Manufacturing KW - Powder Bed Fusion KW - Selected Laser Melting PY - 2019 AN - OPUS4-48073 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ulbricht, Alexander A1 - Altenburg, Simon A1 - Mohr, Gunther T1 - The Influence of the Temperature Gradient on the Distribution of Residual Stresses in AM AISI 316L N2 - Steep temperature gradients and solidification shrinkage are the main contributors to the formation of residual stresses in additively manufactured metallic parts produced by laser beam melting. The aim of this work was to determine the influence of the temperature gradient. Diffraction results show a similar pattern for both specimens, indicating the shrinkage to be more dominant for the distribution of residual stresses than the temperature gradient. Thermography results imply that a higher energy input result in higher compressive residual stresses in the bulk. T2 - Workshop on Additive Manufacturing: Process, materials, simulation & implants CY - BAM, Berlin, Germany DA - 13.05.2019 KW - Computed tomography KW - Online Process Monitoring KW - Additive Manufacturing KW - Powder Bed Fusion KW - Selected Laser Melting KW - Neutron Diffraction PY - 2019 AN - OPUS4-48075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hilgenberg, Kai A1 - Spranger, Felix T1 - Localized laser dispersing of titanium-di-boride with pulsed fiber laser N2 - In this paper, titanium-di-boride is dispersed on a cold-working tool steel by use of a pulsed fiber laser with high beam quality to produce separated and elevated surface features. The potential to adjust the geometry as well as the mechanical properties of the produced structures in dependence on the process parameters (pulse power, pulse duration) is described by means of metallographic and topographical investigations. It can be ascertained that very hard (hardness > 1000 HV1) surface features of different shape (spots and short lines) can be produced. They are characterized by a fine-grained microstructure resulting from a rapid solidification and finely dispersed TiB2 particles. Finally, the paper proposes different applications for this structuring technique. T2 - ICALEO 2017 - International congress on applications of lasers & electro-optics CY - Atlanta, GA, USA DA - 22.10.2017 KW - Laser dispersing KW - Titanium-di-boride KW - Surface structuring KW - Laser implantation PY - 2017 AN - OPUS4-42867 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiel, Erik A1 - Altenburg, Simon A1 - Myrach, P. A1 - Mohr, Gunther A1 - Gumenyuk, Andrey T1 - Crack detection in metal additive manufacturing with laser thermography N2 - BAM ensures and represents high standards for safety in technology and chemistry. Additive manufacturing (AM) changes the requirements for conventional non-destructive testing (NDT) as new processes of defect creation occur. Especially in safety critical areas, such as aerospace and automotive, new manufacturing processes and materials always require reliability tests and new standards which is a big challenge for NDT. T2 - Internationales Laser- und Fügesymposium CY - Dresden, Germany DA - 27.02.2018 KW - Laser Beam Melting KW - Laser Metal Deposition KW - Thermography KW - In-situ monitoring PY - 2018 AN - OPUS4-45619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sprengel, Maximilian A1 - Ulbricht, Alexander A1 - Evans, Alexander A1 - Mohr, Gunther A1 - Kromm, Arne A1 - Bruno, Giovanni A1 - Kannengießer, Thomas T1 - Using Neutron Diffraction to Monitor Stress Relaxation in Additively Manufactured 316L N2 - The relaxation of residual stress in laser powder bed fused stainless steel 316L parts was monitored using monochromatic and time-of-flight neutron diffraction. T2 - ISIS student meeting CY - Online meeting DA - 26.10.2020 KW - Stainless Steel KW - Residual Stress KW - Additive Manufacturing PY - 2020 AN - OPUS4-51469 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yu, C.-H. A1 - Sprengel, Maximilian A1 - Schröder, Jakob A1 - Serrano Munoz, Itziar A1 - Mohr, Gunther A1 - Evans, Alexander A1 - Kromm, Arne A1 - Peng, R. L. A1 - Kannengießer, Thomas A1 - Bruno, Giovanni A1 - Moverare, J. T1 - Distribution of subsurface residual stress as a function of wall thickness in stainless steel 316L LPBF structures N2 - The subsurface residual stress in laser powder bed fused 316L structures was analyzed using X-ray diffraction (XRD) and layer removal. The influence of varying structure thicknesses was investigated. In this study the importance of combining surface roughness measurements with XRD was shown. Moreover, a clear relation between the structure thickness and the subsurface residual stress profiles was observed. T2 - The 11th International Conference on Residual Stress CY - Nancy, Frankreich DA - 28.03.2022 KW - AGIL KW - Residual Stress KW - X-ray Diffraction KW - Additive Manufacturing PY - 2022 AN - OPUS4-54581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gawlitza, Kornelia A1 - Pérez-Padilla, Víctor A1 - Sun, Yijuan A1 - Valderrey, Virginia A1 - Bell, Jérémy A1 - Rurack, Knut T1 - On-Site Detection of PFAAs with Dual Fluorescent MIPs Coupled to a Miniaturized Microfluidics Platform N2 - Per- and polyfluoroalkyl substances (PFAS) represent a class of synthetic organofluorine chemicals extensively utilized in the manufacturing of various materials such as firefighting foams, adhesives, and stain- and oil-resistant coatings. In recent years, PFAS have been considered as emerging environmental contaminants, with particular focus on perfluoroalkyl carboxylic acids (PFCAs), the most prevalent type among PFAS. PFCAs are characterized by a fully fluorinated carbon backbone and a charged carboxylic acid headgroup. Notably, they have been designated as Substances of Very High Concern and added to the REACH Candidate List due to their persistence in the environment, non-biodegradability and toxicological effects. Conventional techniques for the analysis of PFCA, such as GC-MS, HRMS and HPLC-based methods, are laborious, not portable, costly and require skilled personnel. In contrast, fluorescence assays can be designed as easy-to-operate, portable and cost-effective methods with high sensitivity and fast response, especially when analyte binding leads to a specific increase of a probe’s emission. Integration of such probes with a carrier platform and a miniaturized optofluidic device affords a promising alternative for PFCA monitoring. Here, a novel guanidine BODIPY fluorescent indicator monomer has been synthesized, characterized, and incorporated into a molecularly imprinted polymer (MIP) for the specific detection of perfluorooctanoic acid (PFOA). The MIP layer was formed on tris(bipyridine)ruthenium(II) chloride doped silica core particles for optical internal reference and calibration-free assays. Such system allows selective and reliable detection of PFCA from surface water samples, with minimum interference by competitors, matrix effects and other factors. Integration of the assay into an opto-microfluidic setup resulted in a miniaturized and easy-to-operate detection system allowing for micromolar detection of PFOA in less than 15 minutes from surface water sample. T2 - MIP2024: The 12th International Conference on Molecular Imprinting CY - Verona, Italy DA - 18.06.2024 KW - Sensor KW - PFAS KW - Molecularly imprinted polymers KW - Guanidine receptor KW - BODIPY PY - 2024 AN - OPUS4-60438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mrkwitschka, Paul A1 - Hodoroaba, Vasile-Dan A1 - Pellegrino, Francesco A1 - Rossi, Andrea A1 - Jones, Elliot T1 - Towards automated analysis of the lateral dimensions of graphene oxide flakes N2 - Graphene and graphene-oxide (GO) are advanced materials which – similar to other graphene-related 2D materials (GR-2M) - are already used for instance in catalysis processes, biomedical applications, in inks and resins, or as composite materials for the aviation industry. The lateral/structural characterization of graphene oxide (GO) flakes is a challenging task, with steps like sample preparation, representative image selection and exact determination of the particle size distribution of well-defined size and shape descriptors being crucial for an accurate analysis. To ensure that safe-by-design principles are met within the various application fields, the commercial material must be thoroughly characterized and specified through well-known and standardized procedures. GO flakes with different degrees of complexity were selected to assess the requirements for an accurate evaluation of their physico-chemical properties. These samples show inherent features with complex nanoscale characteristics such as porosity and edge roughness; further, the lateral size (quantified via equivalent circular diameter (ECD), minimum Feret and maximum Feret) of isolated and overlapping particles deposited on a substrate span over several orders of magnitude (nano to micron scale). The samples showed different degrees of agglomeration (and possible aggregation) with sizes ranging between submicron to a few tens of micrometers. One focus is the automated segmentation and evaluation of images obtained by electron microscopy. The GO samples appear translucent with well-defined contrast between single and overlapping flakes both with the secondary electron detector of type InLens as well as with SEM in the transmission mode (STEM) utilizing a dedicated sample holder. To this end it is of utmost importance for the accurate image segmentation to carefully select thresholds both manually and through semi-automatic approaches using well-known threshold algorithms such as “IsoData” and pre-defined segmentation applications such as the ParticleSizer software package. Further specific challenges in identifying and extracting key features of selected graphene oxide flakes are being discussed and approaches towards accurate and representative characterization are presented. T2 - E-MRS 2024 Spring Meeting CY - Strasbourg, France DA - 27.05.2024 KW - Graphene /-oxide KW - Morphology KW - Electron microscopy KW - Imaging KW - Advanced materials PY - 2024 AN - OPUS4-60435 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wurzler, Nina A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Kunte, Hans-Jörg A1 - Özcan Sandikcioglu, Özlem T1 - Chemical interaction mechanisms of metal reducing bacteria on steel surfaces N2 - Metal reducing bacteria (MRB) are able to utilize various materials such as iron, uranium and manganese as well as many organic compounds as electron acceptors. This process leads to the conversion of Fe(III) containing passive film species to soluble Fe(II) oxides and hydroxides. The reduction process triggers the acceleration of general and local corrosion processes. Electron transfer mechanisms are not yet fully understood. In literature it has been controversially discussed to which extend secreted electron shuttles contribute to the extracellular electron transfer (EET). To understand the chemical and electrochemical interaction mechanisms of MRB with steel surfaces this project combines a variety of in-situ techniques. The changes in oxide chemistry on Fe/steel surfaces in the presence of biomolecules and MRB are under investigation using a newly designed electrochemical cell for in situ XANES (x-ray absorption near edge structure) spectroscopy. Electrochemical quartz crystal microbalance (eQCM) studies support the spectroscopic investigations to gain information about the kinetics of attachment processes and changes in biofilm viscosity. The biofilm structure and composition as well as cell viability are investigated by complementary ex situ spectroscopic and microscopic analysis. Combining spectroscopic techniques and eQCM data with electrochemical measurements, biological processes and the resulting degradation of steel surfaces can be observed in a non-destructive manner. Selecting model systems and a defined biological medium allows the determination of individual effects of diverse surface and environmental parameters. The fundamental understanding of bacterial attachment mechanisms and initial steps of biofilm formation will contribute to the development of new antifouling strategies. T2 - 12th International Conference on Biology and Synchrotron Radiation CY - San Francisco, CA, USA DA - 21.08.2016 KW - Microbially influenced corrosion (MIC) KW - Metal reducing bacteria KW - XANES KW - Electrochemistry PY - 2016 AN - OPUS4-37238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Naik, Aakash Ashok A1 - George, Janine T1 - New descriptors for materials properties based on bonding indicators N2 - Includes a summary of the Ph.D. project that deals with generating a database populated with materials bonding properties and how we intend to gain deeper insights into material properties through this research. T2 - SALSA 2022 CY - Berlin, Germany DA - 15.09.2022 KW - Bonding analysis KW - Automation KW - Materials Informatics KW - Computational Chemistry PY - 2022 AN - OPUS4-56142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ertural, Christina A1 - Deringer, V. L. A1 - George, Janine T1 - Automation of machine learning driven interatomic potential generation for predicting vibrational properties N2 - Investigating the phononic properties is beneficial for predicting low thermal conductivity thermoelectric materials.1–3 Employing density functional theory4 takes many calculation steps and consumes a lot of computational resources.5,6 Using machine learning driven interatomic potentials (MLIP, e.g., Gaussian approximation potential,8 GAP) opens up a faster route to phonons7 but in most cases, the potentials are specifically tailored for a certain compound. In this work, we automate the generation of such MLIPs in a Python code-based workflow, based on the automation tools atomate29 and pymatgen10 which combines the automatic DFT computations with the automated fitting of GAPs. Automation enables easier testing, benchmarking and validation.11 We aim to provide the workflow-generated potentials for storage in databases. T2 - 16th International conference on materials chemistry (MC16) CY - Dublin, Ireland DA - 03.07.2023 KW - Interatomic potentials KW - Machine learning KW - Phonons KW - Thermoelectrics PY - 2023 AN - OPUS4-57932 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Naik, Aakash Ashok A1 - George, Janine T1 - Building quantum chemical orbital based bonding descriptor database N2 - Motivation, methodology and and results of our quantum chemical bonding descriptors database presented in form of a Poster T2 - RSC Twitter Conference 2023 CY - Online meeting DA - 28.02.2023 KW - Bonding analysis KW - Automation KW - Materials Informatics KW - Computational Chemistry KW - Database PY - 2023 UR - https://twitter.com/NaikAak/status/1630400167080869893 UR - https://twitter.com/NaikAak/status/1630540436434558977 AN - OPUS4-57101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Torge, Manfred A1 - Feldmann, Ines A1 - Bücker, Michael A1 - Seeger, Stefan T1 - The effect of particle deposition and climate on glass degradation N2 - A number of environmental monitoring projects were performed on historic stained-glass windows in Germany. The quality of the protective glazing was assessed by recording environmental parameters in the interspace between the original and the protective glazing and on the inside of the original window. For this purpose, temperature, humidity and air velocity were measured. Particles were sampled with different methods and analysed by scanning electron microscopy combined with energy dispersive X-ray spectroscopy to determine their chemical composition. The effect of particles on model glass samples was investigated in climate chambers under accelerated weathering conditions. T2 - International Symposium on Glass Degradation in Atmospheric Conditions CY - C2RMF, Paris, France DA - 15.11.2017 KW - Particle measurement KW - Dust analysis KW - Climate chamber simulation KW - Protective glazing PY - 2017 AN - OPUS4-43171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Veliz Montes, Cinthya A1 - Bottari, G. A1 - Trukina, O. A1 - Torres, Tomás A1 - Schneider, Rudolf T1 - Unsubstituted, covalently-linked phthalocyanine-C60 fullerene dyads N2 - Were prepared four unsubstituted Pc - C60 fullerene systems, using two different synthetic strategies, via Prato (1,3 - dipolar cycloaddition) or Bingel reactions. The precursor Pcs 1 and 2 were successfully synthesized by cyclotetramerization reaction between TBDPS - protected and unsubstituted phthalonitriles. The surface studies are currently ongoing. T2 - PcsTT2016 Symposium CY - Elche, Spain DA - 27.01.2016 KW - Fullerene KW - Phthalocyanine PY - 2016 AN - OPUS4-38556 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völzke, Jule L. A1 - Hodjat Shamami, Parya A1 - Gawlitza, Kornelia A1 - Feldmann, Ines A1 - Zimathies, Annett A1 - Meyer, Klas A1 - Weller, Michael G. T1 - Corundum as a novel affinity platform for the isolation of human IgG from plasma N2 - Nonporous corundum powder was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices.The common crosslinker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter was oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). As a proof of concept, IgG was extracted with protein A from crude human plasma. The advantages of corundum include the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, convenient handling, and flexible application. T2 - Adlershofer Forschungsforum 2022 CY - Berlin, Germany DA - 11.11.2022 KW - Affinity support KW - Affinity chromatography KW - Affinity extraction KW - Phosphonic acids KW - Polyglycerol KW - Reductive amination KW - Amino acid analysis KW - Tyrosine KW - Protein quantification KW - SDS-PAGE KW - Antibodies KW - Antibody purification KW - Downstream processing KW - Bovine serum albumin KW - BSA KW - Protein a KW - TEM KW - ESEM KW - Aluminum oxide KW - Sapphire KW - Human plasma KW - Protein immobilization KW - Protein hydrolysis KW - Glutaraldehyde KW - Aromatic amino acid analysis AAAA PY - 2022 AN - OPUS4-56154 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schob, Daniela A1 - Tabin, Jakub A1 - Kowalko, Jakub A1 - Roszak, Robert A1 - Ziolkowski, Grzegorz A1 - Ziegenhorn, Matthias A1 - Hilgenberg, Kai T1 - Comparative Analysis FFF vs. cold rolled 316L Samples N2 - This study provides insights into the properties of 316L stainless steel produced by additive manufacturing using fused filament fabrication (FFF). One key finding is particularly noteworthy: in significant contrast to cold-rolled 316L, FFF316L develops a pronounced martensite phase after fabrication. The comprehensive comparative analysis shows that FFF316L not only retains the ferrite volume content, but that this is also significantly influenced by the build-up direction. Despite the sintering process, which typically involves densification of the material, a pore volume fraction of 8.45 % remains, which influences the mechanical properties. Although FFF316L has lower elastic modulus and tensile strength values compared to cold-rolled 316L, its ductility is still competitive. The study further reveals that deformation-induced martensite forms at the intersections of the deformation twins and ferrite islands form at the grain boundaries during the compression and sintering phases. These findings highlight the challenges associated with FFF316L in specific application fields and signal the need to continue to carefully evaluate and improve the development of manufacturing technologies. T2 - 4th Symposium on Materials and Additive Manufacturing - Additive 2024 CY - Berlin, Germany DA - 12.06.2024 KW - Additive manufacturing KW - Fused Filament Fabrication KW - Computed Tomography KW - 316L Stainless Steel KW - Deformation-Induced Martensite PY - 2024 AN - OPUS4-60302 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Process monitoring in LBM using thermography and optical tomography N2 - Additive manufacturing (AM) opens the route to a range of novel applications. However, the complexity of the manufacturing process poses a challenge to produce defect-free parts with a high reliability. Since process dynamics and resulting microstructures of AM parts are strongly influenced by the involved temperature fields and cooling rates, thermography is a valuable tool for process monitoring. Another approach to monitor the energy input into the part during process is the use of optical tomography. Common visual camera systems reach much higher spatial resolution than infrared thermography cameras, whereas infrared thermography provides a much higher temperature dynamic. Therefore, the combined application increases the depth of information. Here, we present first measurement results using a laser beam melting setup that allows simultaneous acquisition of thermography and optical tomography from the same point of view using a beam splitter. A high-resolution CMOS camera operating in the visible spectral range is equipped with a near infrared bandpass filter and images of the build plate are recorded with long-term exposure during the whole layer exposing time. Thus, areas that reach higher maximum temperature or are at elevated temperature for an extended period of time appear brighter in the images. The used thermography camera is sensitive to the mid wavelength infrared range and records thermal videos of each layer exposure at an acquisition rate close to 1 kHz. As a next step, we will use computer tomographic data of the built part as a reference for defect detection. This research was funded by BAM within the focus area Materials. T2 - 3rd International Symposium Additive Manufacturing (ISAM 2019) CY - Dresden, Germany DA - 30.01.2019 KW - Additive manufacturing KW - Laser beam melting KW - Thermography KW - Optical Tomography PY - 2019 AN - OPUS4-47299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Thermography in metal AM: Comparison of high-speed NIR thermography and MWIR thermography N2 - Additive manufacturing (AM) opens the route to a range of novel applications.However, the complexity of the manufacturing process poses a challenge for the production of defect-free parts with a high reliability. Since process dynamics and resulting microstructures of AM parts are strongly influenced by the involved temperature fields, thermography is a valuable tool for process surveillance. The high process temperatures in metal AM processes allow one to use cameras usually operating in the visible spectral range to detect the thermally emitted radiation from the process. In our work, we compare the results of first measurements during the manufacturing processes of a commercial laser metal deposition (LMD) setup and a laser beam melting (LBM) setup using a MWIR camera with those from a VIS high-speed camera with band pass filter in the NIR range. T2 - Additive Manufacturing Benchmarks 2018 CY - Gaithersburg, MA, USA DA - 18.06.2018 KW - Thermography KW - Additive manufacturing KW - Laser metal deposition KW - Laser beam melting KW - ProMoAM PY - 2018 AN - OPUS4-45401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hernández García, María Amparo A1 - Rurack, Knut A1 - Bell, Jérémy A1 - Weller, Michael G. T1 - SAF-based optical biosensor with 3D-printed free-form optics for targeted explosives immuno-detection N2 - Guaranteeing safety and security of citizens requires a significant effort and innovative tools from national and international agencies and governments, especially when it comes to the field of explosives detection. The need to detect Improvised Explosive Devices (IEDs) and Home-made Explosives (HMEs) at a point of suspicion, has grown rapidly due to the ease with which the precursors can be obtained and the reagents synthesised. The limited availability of immunoanalytical tools for HME detection presents an opportunity for the development of new devices, which enable a rapid detection and recognise the target analyte with high specificity and sensitivity. In this work, we introduce an optical biosensor for highly specific and sensitive HME detection. The immunoassay system is placed in a hydrogel environment permeable to the analyte and transparent to light interrogating the fluorescently labelled antibodies. The readout of the immunoanalytical system is realized with Supercritical Angle Fluorescence (SAF), an advanced microscopy technique. To accomplish this, we made use of recent, commercial high resolution (< 22 µm) Liquid Crystal Display 3D printers to fabricate a parabolic optical element with high refractive index (RI>1.5) and transmission values (>90%) from photo-resin. Aiming at a new generation of sensors, which not only can meet the requirements of trace detection, but can also be used for substance identification, the combination of immunoanalytical recognition with SAF detection offers a modularity and versatility that is principally well suitable for the measurements of target analytes at trace levels. T2 - 8th International conference in Biosensing Technology CY - Seville, Spain DA - 12.05.2024 KW - 3D printing KW - Biosensor KW - Fluorescence KW - Explosives PY - 2024 AN - OPUS4-60561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fernandez-Poulussen, D. A1 - Hodoroaba, Vasile-Dan A1 - Drobne, D. A1 - Novak, S. A1 - Kranjc, E. A1 - Pellegrino, F. A1 - Gullumian, M. A1 - Jones, E. A1 - Hardy, B. A1 - Valsami-Jones, E. A1 - Jurkschat, K. A1 - van der Zande, M. T1 - Holistic, reliable and practical Characterization Framework for Graphene Family Materials, a correlated approach including Imaging based techniques N2 - ACCORDs is an Horizon Europe project working in the development of an imaging-based characterization framework (ACCORDs framework) for the holistic correlative assessment of Graphene Family Materials (GFMs) as a representative of 2D nanomaterials (NMs) to assess and predict 2D NMs health and environmental risks. The ACCORDs framework will operationalise safe and sustainable by design (SSbD) strategies proposed in past or ongoing H2020 projects or within OECD by correlating low-, medium-, and high-resolution physico-chemical-biological imaging-based methods with non-imaging methods in a tiered approach. ACCORDs will deliver the ACCORDs framework and user guidance, new imaging-based characterisation methods, reference in vitro tests, new reference 2D NMs for different matrices, a new minimum information reporting guideline for FAIR data sharing and reuse of images as well as an atlas with reference images for diagnostics of compromised safety of GFMs/GFM products. The new guidelines and standard proposals will be submitted to standardisation bodies to allow creation of regulatory ready products. The novelty of ACCORDs is in translating the principles of medical imaging-based diagnostics to 2D material hazard diagnostics. ACCORDs will accelerate industrial sectors in the area of aviation, marine construction, drone production, flexible electronics, photovoltaics, photocatalytics and print inks-based sensors. The value ACCORDs proposes to the graphene industry are practical, easy, imaging-based tools for GFM quality monitoring next to the production line with a possibility to be correlated with advanced highresolution imaging characterization methods in case hazard i.e. deviation from controls (benchmark values) are diagnosed. The ACCORDs framework and tools will contribute to the European Green Deal by addressing the topic: “Graphene: Europe in the lead” and to a new European strategy on standardization, released on 2nd February, 2022. T2 - MaterialsWeek 2024 CY - Limassol, Cyprus DA - 17.06.2024 KW - Graphene KW - Graphene-related 2D materials KW - SSbD KW - Imaging KW - ACCORDs PY - 2024 AN - OPUS4-60573 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Serrano Munoz, Itziar A1 - Mouiya, Mossaab A1 - Prasek, Marko A1 - Kupsch, Andreas A1 - Bruno, Giovanni T1 - High temperature in-situ heat treatment of a refractory material by means of synchrotron refraction radiography N2 - The stress–strain behavior of certain ceramics, such as aluminum titanate (AT, Al2TiO5), has features that are unusual for brittle material. In particular, a substantial nonlinearity under uniaxial tension, and load–unload hysteresis caused by the increase of the incremental stiffness at the beginning of unloading. These features are observed experimentally and attributed to microcracking. In this study, we investigate the mechanical response of an AT material at room and high temperature. Microstructure and microcracking are analyzed by means of electron microscopy, and both synchrotron micro computed tomography (µCT) and refraction radiography (SXRR). Synchrotron refraction radiography is combined with in-situ heating at high-temperatures (up to 1400°C) to be able to monitor the relative closure of microcracks as a function of increasing/decreasing temperatures. T2 - 21st European Conference on Composite Materials (ECCM21) CY - Nantes, France DA - 02.07.2024 KW - Refractory materials KW - Microcracking KW - Synchrotron µCT and refraction radiography KW - In-situ heating up to 1400°C PY - 2024 AN - OPUS4-60576 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - George, Janine A1 - Naik, Aakash Ashok A1 - Ertural, Christina A1 - Dhamrait, Nidal A1 - Benner, Philipp T1 - A Quantum-Chemical Bonding Database for Solid-State Materials N2 - A deep insight into the chemistry and nature of individual chemical bonds is essential for understanding materials. Bonding analysis is expected to provide important features for large-scale data analysis and machine learning of material properties. Such information on chemical bonds can be calculated using the LOBSTER (www.cohp.de) software package, which post-processes data from modern density functional theory computations by projecting plane wave-based wave functions onto a local atomic orbital basis. We have performed bonding analysis on 1520 compounds (insulators and semiconductors) using a fully automated workflow combining the VASP and LOBSTER software packages. We then automatically evaluated the data with LobsterPy (https://github.com/jageo/lobsterpy) and provide results as a database. The projected densities of states and bonding indicators are benchmarked on VASP projections and available heuristics, respectively. Lastly, we illustrate the predictive power of bonding descriptors by constructing a machine-learning model for phononic properties, which shows an increase in prediction accuracies by 27 % (mean absolute errors) compared to a benchmark model differing only by not relying on any quantum-chemical bonding features. T2 - Sommersymposium des Fördervereins Chemieolympiade CY - Online meeting DA - 15.04.2023 KW - Automation KW - Chemical Bonds KW - DFT KW - Quantum Chemistry PY - 2023 AN - OPUS4-57310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ertural, Christina A1 - George, Janine T1 - Vibe Check via Machine Learning: Testing the Prototype N2 - Vibrational properties play a key role in determining the stability and thermal conductivity behaviour of materials. The quasi- harmonic approximation gives insight into the phononic properties of a compound, but in the established way, i.e. density functional theory based methods, it takes many calculation steps and consumes a lot of resources to arrive at the desired results. Machine learning (ML) trained interatomic potentials (e.g. Gaussian approximation potential, GAP) pose an alternative to the traditional computation way of phonons. We develop a Python code based workflow which combines automation tools like atomate2 with ML to ease providing interactomic potentials for (quantum chemical) computations and databases. T2 - #RSCPoster Twitter conference 2023 CY - Online meeting DA - 28.02.2023 KW - Interatomic potentials KW - Machine learning KW - Phonons KW - Workflow PY - 2023 UR - https://twitter.com/cer5814012/status/1630547004462858240 AN - OPUS4-57059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bustamante, Joana A1 - Naik, Aakash Ashok A1 - Ertural, Christina A1 - Ueltzen, Katharina A1 - George, Janine T1 - Thermodynamic and Thermoelectric Properties of the Canfieldite, (Ag8SnS6 ), in the Quasi-Harmonic Approximation N2 - Argyrodite-type materials have lately sparked a lot of research interest due to their thermoelectric properties.One promising candidate is canfieldite (Ag8SnS6), which has a Pna21 orthorhombic crystal structure at room temperature (RT). Recently, a new low-temperature (LT) phase transition of canfieldite at 120K has been found. Here, we investigate structural, vibrational and thermodynamic properties of Ag8SnS6 at room- and low-temperature employing density functional theory (DFT) and lattice dynamics computations. Thermal properties calculations were based on the quasi-harmonic approximation (QHA) as implemented in phonopy. We achieve good agreement with experiments. Thermal properties such as the constant-pressure heat capacity (Cp) and thermal conductivity are very close to experimental measurements. Furthermore, we compared RT and LT Ag8SnS6 Grüneisen parameters with argyrodites analogues, Ag8XS6 (X = Sn, Si, Ge), to arrive at an improved T2 - 16th International conference on materials chemistry (MC16) CY - Dublin, Ireland DA - 03.07.2023 KW - Thermoelectric materials KW - DFT KW - QHA KW - Grüneisen parameter PY - 2023 AN - OPUS4-57887 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Naik, Aakash Ashok A1 - Ertural, Christina A1 - Dhamrait, Nidal A1 - Benner, Phillip A1 - George, Janine T1 - A Quantum-Chemical Bonding Database for Solid-State Materials N2 - Understanding the chemistry and nature of individual chemical bonds is essential for materials design. Bonding analysis via the LOBSTER software package has provided valuable insights into the properties of materials for thermoelectric and catalysis applications. Thus, the data generated from bonding analysis becomes an invaluable asset that could be utilized as features in large-scale data analysis and machine learning of material properties. However, no systematic studies exist that conducted high-throughput materials simulations to curate and validate bonding data obtained from LOBSTER. Here we present an approach to constructing such a large database consisting of quantum-chemical bonding information. T2 - 16th International conference on materials chemistry (MC16) CY - Dublin, Ireland DA - 03.07.2023 KW - Bonding analysis KW - Automation KW - Materials Informatics KW - Computational Chemistry KW - Database PY - 2023 AN - OPUS4-57889 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg A1 - Ciornii, Dmitri A1 - Knigge, Xenia A1 - Hodoroaba, Vasile-Dan A1 - Bennet, F. A1 - Meirer, F. A1 - Duijndam, A. A1 - Thünemann, Andreas A1 - Drexel, R. A1 - Fadda, M. A1 - Sacco, A. A1 - Giovannozzi, A.M. A1 - Donskyi, I. A1 - Schusterbauer, R. A1 - Nickl, P. A1 - Reichardt, P. A1 - Altmann, Korinna T1 - Revealing surface functionalities of micro- and nanoplastic particles’ surface by means of XPS N2 - Over the last 20 years, many researchers, politicians, and citizens themselves have become increasingly aware of the growing plastic problem of our time. Inadequate recycling concepts, collection points, and careless dumping of plastic products in the environment lead to an accumulation of plastic. External weather influences can cause these to degrade and fractionate, so that today microplastics (1-1000 µm, ISO/TR 21960:2020) [1] of different polymer materials can be detected in all parts of the world. The precautionary principle applies to microplastics. The particles can break down further to form nanoplastics (<1 µm, ISO/TR 21960:2020) [1]. Whether microplastics or nanoplastics pose a toxicological hazard is being investigated in a variety of ways. Valid results are still pending, however, investigations into the frequency, transport, possible sinks and entry paths must be taken into account. This is why monitoring of microplastics is already required in the revision of the Drinking Water Framework Directive [2]. The same is still pending in the final version of the revision of the Waste Water Framework Directive this year, but is expected. Nanoplastics are particularly under discussion for having a toxic effect on humans and animals, as these particles are small enough to be absorbed by cells. For targeted toxicological studies, it is important to have test and reference materials that resemble the particles found in the environment. To mimic environmental samples, these materials should also have an irregular shape and show aging at the surface, which can be detected with XPS or SEM/EDS. BAM in collaboration with the EMPIR project "PlasticTrace" works on a reference material candidate of nano-sized polypropylene (nano-PP) [3]. The nano-PP vials were tested for homogeneity with PTA and further characterized with bulk and surface-sensitive techniques. An SEM image and a corresponding XPS spectrum are presented in Figure 1. Raman measurements as well as XPS indicate an aged surface. T2 - ECASIA 2024 CY - Gothenburg, Sweden DA - 09.06.2024 KW - Surface chemistry KW - Micro- and nanoplastics KW - X-ray Photoelectron Spectroscopy KW - MNP production technique PY - 2024 AN - OPUS4-60535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Amariamir, Sasan A1 - Benner, Philipp A1 - George, Janine T1 - Prediction of materials synthesizability N2 - In the pursuit of discovering materials with desirable properties, extending the available material libraries is crucial. High-throughput simulations have become an integral part in designing new materials in the past decades. However, there is no straightforward way of distinguishing synthesizable materials from all the proposed candidates. This project focuses on employing AI-driven methods to estimate synthesizability of materials. Up to now, material scientists and engineers have relied on domain knowledge as well as empirical heuristics to guess the stability and synthesizability of molecules and crystals. The famous Pauling rules of crystal stability are an example of such heuristics. However, after the accelerating material discovery in all the years since Pauling, these rules now fail to account for the stability of most known crystals. A new predictive set of heuristics for crystal stability/synthesizability is unlikely to be uncovered by human perception, given the magnitude and dimensionality of crystallographic data. Hence, a data-driven approach should be proposed to find a predictive model or set of heuristics which differentiate synthesizable crystal structures from the rest. The main challenge of this research problem is the lack of a negative set for classification. Here, there are two classes of data: the positive class which contains synthesizable materials and the negative class which contains materials which are not synthesizable. While the data from the positive class is simply the data of crystals which have been experimentally synthesized, we do not have access to data points which are certainly unsynthesizable. Strictly speaking, if an attempt of synthesizing a crystal fails, it does not necessarily follow that the crystal is not synthesizable. Also, there is no database available which contains the intended crystal structures of unsuccessful synthesis attempts. This project proposes a semi-supervised learning scheme to predict crystal synthesizability. The ML model is trained on experimental and theoretical crystal data. The initial featurization focuses on local environments which is inspired by the Pauling Rules. The experimental data points are downloaded through the Pymatgen API from the Materials Project database which contains relaxed structures recorded in Inorganic Crystal Structure Database – ICSD. The theoretical data is queried from select databases accessible through the Optimade project’s API. T2 - MSE Congress 2022 CY - Darmstadt, Germany DA - 27.09.2022 KW - Synthesizability KW - PU Learning KW - Cheminformatics PY - 2022 AN - OPUS4-56731 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Benjamin, Merz A1 - Poka, Konstantin A1 - Mohr, Gunther A1 - Hilgenberg, Kai A1 - Polte, Julian T1 - Advanced camera calibration for lens distortion correction in hybrid additive manufacturing processes N2 - Hybrid additive manufacturing is becoming increasingly important in the field of additive manufacturing. Hybrid approaches combine at least two different manufacturing processes. The focus of this work is the build-up of geometries onto conventionally manufactured parts using laser-based powder bed fusion of metals (PBF-LB/M). The hybrid build-up requires a precise position detection system inside the PBF-LB/M machines to determine the exact position of the existing component. For this purpose, high-resolution camera systems can be utilized. However, the use of a camera system is associated with several challenges. The captured images are subject to various distortions of the optical path. Due to these distortions, it is not possible to use the images for measurements and, therefore, it is not possible to calculate the positions of objects. In this study a homography matrix is calculated to correct keystone distortion in the images. Different calibration patterns have been tested for the calculation of the homography matrix. The influence of the number of calibration points on the precision of position detection of objects is determined. Furthermore, the influence of an additional camera calibration by using ChArUco boards is evaluated. The result is a camera calibration workflow with associated calibration pattern for a precise position detection of parts inside PBF-LB/M machines allowing a hybrid build-up with minimum physical offset between base component and build-up. T2 - euspen’s 24th International Conference & Exhibition CY - Dublin, Ireland DA - 10.06.2024 KW - Aditive Manufacturing KW - Hybrid build-up KW - Position detection KW - Camera calibration PY - 2024 AN - OPUS4-60600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Aristia, Gabriela A1 - Bäßler, Ralph A1 - Roth, C. T1 - SiO2-containing organic coatings for geothermal application N2 - Geothermal brine is considered to be an aggressive environment as it contains various dissolved salts. Even though carbon steel is commonly used as a construction material due to its machinability and economical reason, it is susceptible to uniform and localized corrosion in a high temperature and high pressure system. Therefore, a coating system is introduced to protect the carbon steel against corrosion in such environment. -It is necessary to find the optimum composition of SiO2 addition in the organic coatings to enhance the material performance, i.e. coatings adhesion, thickness optimization, thermal resistance. Current project aims at the addition of Polyaniline (PANi) as the active agent to improve the corrosion resistance of materials against a high saline medium at elevated temperatures. T2 - BAM PhD Day CY - Berlin, Germany DA - 21.09.2017 KW - Geothermal KW - Corrosion KW - Coating PY - 2017 AN - OPUS4-43362 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kullolli, Borana A1 - Cuéllar, Pablo A1 - Baeßler, Matthias T1 - Numerical modelling of soil-structure interfaces N2 - The governing load bearing mechanism of multi-pile foundations is often the shaft friction. Under cyclic loading the soil particles next to the foundation rearrange and tend to compact leading to a decrease of the surrounding normal stress. The reduction of the normal stress leads to a lower threshold for shear stress (friction fatigue), which results in a degraded shaft bearing capacity. The common interface models used for numerical simulations (e.g. Mohr-Coulomb) are not able to capture such behavior. This work aims to develop an interface material model that incorporates such features of the contact behavior at the soil-structure interface. T2 - Alert Geomaterial Workshop CY - Aussois, France DA - 01/10/2018 KW - Soil-structure interaction KW - Interface KW - Material model KW - Numerical modelling PY - 2018 AN - OPUS4-47066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Saadeh, Qais A1 - Pauw, Brian Richard A1 - Thünemann, Andreas A1 - Günster, Jens T1 - In-situ SAXS techniques N2 - This project studies the orientation of nanoparticles under the influence of external stimuli such as electric fields, magnetic fields and ultra-sonic vibrations. A set of functional sample holders that fit inside the sample chamber of a state-of-the-art Small Angle X-ray Scattering (SAXS) machine, called the “Multi-scale Analyzer for Ultrafine Structures” (MAUS). The MAUS has been custom engineered to serve as a miniaturized Synchrotron, thus enabling standard material to be characterized to a high standard. Our work is needed to detail the fine characterization of reference nano-particles, not only on the nano-scale, but also coupled with external agents. A second aim of this project is to verify a few proof-of-concept designs for the alignment of nano-particles. Where the alignment of nano-particles In-Situ is intended to further develop 3D printing technologies, and SAXS is an ideal choice to study the alignment of an oriented ensemble. For more information about the MAUS; https://www.bam.de/Content/DE/Pressemitteilungen/2018/AnalyticalSciences/2018-01-31-mit-maus-an-die-spitze-der-nano-forschung.html T2 - NanoWorkshop 2018 (Workshop on Reference Nanomaterials. Current situation and needs: development, measurement, standardization) CY - Berlin, Germany DA - 14.05.2018 KW - SAXS KW - Nano-particles alignment KW - Magnetic nano-particles PY - 2018 AN - OPUS4-44912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph A1 - Keserović, Amela A1 - Sobetzki, Joana A1 - Sarmiento Klapper, Helmuth A1 - Dimper, Matthias T1 - Evaluation of metallic materials for geothermal applications N2 - Since geothermal wells are a feasible energy source to replace fossil fuel supply, many technologies have been developed to take advantage of geothermal energy. Nevertheless, service conditions in geothermal facilities are due to the chemical composition of hydrothermal fluids and temperatures, in many cases, extreme in terms of corrosion. Therefore, materials selection based on preliminary material qualification is essential to guarantee a secure and reliable operation of the facilities. The corrosion behavior of different high-alloyed metals including Duplex and austenitic stainless steels as well as a nickel alloy have been evaluated in artificial geothermal fluids simulating the conditions in some locations with geothermal potential in Germany as well as two sites in Indonesia. The suitability of carbon steel 25CrMo4, stainless steels X2CrNiMo17-12-2, X2CrNiMo-22-5, X2CrNiMoCuWN25-7-4 and super austenitic steel X1CrNiMoCu32-28-7 in these geothermal fluids obtained by electrochemical measurements and exposure tests is limited. The nickel alloy NiCr23Mo16Al shows an excellent corrosion resistance against pitting corrosion. Excluding its high cost, it is a very good alternative to be used in the construction of geothermal facilities having highly saline brines. Stainless and Duplex steels exhibit a limited corrosion resistance concerning pitting and crevice corrosion. Beside of the higher alloyed materials, also the lowalloyed steel 25CrMo4 could be employed as a constructional material for the geothermal power plant in stagnant highly acidic non Saline environments, as long as the wall thickness of the material vs. corrosion rate is taken into account. T2 - European Geothermal Congress CY - Strasbourg, France DA - 19.09.2016 KW - Localized corrosion KW - Stainless steel KW - Ni-based alloy KW - Geothermal energy PY - 2016 AN - OPUS4-37751 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Koter, Robert A1 - Hartelt, Manfred A1 - Spaltmann, Dirk A1 - Kirner, Sabrina A1 - Pentzien, Simone A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Tribological properties of femtosecond laserinduced periodic surface structures on metals N2 - Laser-induced periodic surface structures (LIPSS, ripples) were generated on steel and titanium surfaces upon irradiation with multiple linear polarized femtosecond laser pulses (pulse duration 30 fs, central wavelength 790 nm). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning geometry for the processing of large surface areas covered homogeneously by the nanostructures. The irradiated surface regions were subjected to optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM) revealing sub-wavelength spatial periods. The nanostructured surfaces were tribologically tested under reciprocal sliding conditions against a sphere of hardened 100Cr6 steel at 1 Hz using paraffin oil and engine oil as lubricants. After 1000 sliding cycles at a load of 1.0 N, the corresponding wear tracks were characterized by OM and SEM. For specific conditions the laser-generated nanostructures endured the tribological treatment. Simultaneously, a significant reduction of the friction coefficient was observed in the laser-irradiated (LIPSS-covered) areas when compared to the non-irradiated surface, indicating the potential benefit of laser surface structuring for tribological applications. T2 - SPIE Photonics West Conference, Symposium "Laser Applications in Microelectronic and Optoelectronic Manufacturing" (LAMOM) XXI CY - San Francisco, CA, USA DA - 13.02.2016 KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures (LIPSS) KW - Tribology KW - Friction KW - Wear PY - 2016 AN - OPUS4-36041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gräf, S. A1 - Kunz, C. A1 - Büttner, T.N. A1 - Naumann, B. A1 - Boehm, A.V. A1 - Gnecco, E. A1 - Bonse, Jörn A1 - Neumann, C. A1 - Turchanin, A. A1 - Müller, F.A. T1 - Large-area fabrication of low- and high-spatial-frequency laser-induced periodic surface structures on carbon fibers N2 - The properties of fiber-reinforced polymers (CFRP) or concretes (ECC) strongly depend on the interface between the fiber and the surrounding matrix. Different methods such as plasma oxidation, chemical or electrolytic etching and chemical vapor deposition have been investigated to increase, for example, the bonding strength. The present study deals with the functionalization of the fiber surface based on laser-induced periodic surface structures (LIPSS). They can be characterized as a modulation of the surface topography on the nano- and microscale that results from the irradiation of the surface with linearly polarized laser radiation close to the ablation threshold. According to their spatial period, LIPSS are classified into low-spatial frequency LIPSS (LSFL) and high-spatial frequency LIPSS (HSFL). The great potential of both types of LIPSS structures regarding functional surface properties was demonstrated in numerous investigations. The objective of the present study was the homogenous manufacturing of both types of LIPSS on large areas of carbon fiber arrangements without damage. The results are discussed based on a detailed analysis of the topographic and chemical surface properties. T2 - 15th International Conference on Laser Ablation (COLA 2019) CY - Hawaii, USA DA - 08.09.2019 KW - Laser-induced periodic surface structures (LIPSS) KW - Carbon fibers KW - Femtosecond laser ablation KW - Surface functionalization PY - 2019 AN - OPUS4-49676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Topolniak, Ievgeniia A1 - Elert, Anna Maria A1 - Knigge, Xenia A1 - Cifci, G. C. A1 - Radnik, Jörg A1 - Sturm, Heinz T1 - Polydopamine micropatterning for selective substrate bio-functionalization N2 - Inspired by the chemistry of mussel adhesive proteins, polydopamine (PDA) exhibits strong adhesion to nearly any kind of organic or inorganic surface and shows high ability for surface post-modification and secondary reactions. As a result, PDA has been widely used as a base adlayer to enable versatile surface chemistry and functionalization. It has shown great potential in wide range of applications including biomedical field (e.g., drug delivery, adhesives, photothermal therapy, bone and tissue engineering, cell adhesion, biosensing). However, implementation of PDA in microdevices is still hindered by insufficient spatial and temporal control of excited deposition methods. In this work we present a novel approach to fabricate tunable micropatterned substrates where mussel-inspired chemistry provides base for various surface modification [2]. Current approach applies Multiphoton Lithography (MPL) to initiate local PDA formation, and, therefore, does not require use of microstamp or photomask. As a result, the microstructures of complex designs can be produced with the spatial resolution down to 0.8 μm (Figure 1). The desired design can be easily altered by adjusting the stl model or the fabrication code. Unlike the conventional deposition of PDA based on dopamine auto-oxidation, our method does not require presence of strong oxidants, metal ions or alkaline pH. Herein-demonstrated deposition approach will significantly facilitate applications of polydopamine and other mussel-inspired materials in microdevices and high-resolution active microcomponents (e.g., in MEMS and microfluidics). Adjustment of MPL parameters revealed that the morphology and thickness of resulted PDA microstructures can be controlled by altering the laser power and its scanning velocity. As a result, it also enables the production of micropatterns with structural gradient. Apart from the glass substrate, we performed PDA patterning at surfaces of different nature such as polychlorotrifluoroethylene, polydimethylsiloxane, polyethylene terephthalate, silicon wafers, and fluorinated glass coverslips. We tested different composition of dopamine solution for its ability of PDA buildup. Solutions containing Tris buffer, phosphate buffer or DI water only as well as different pH (6.0, 7.0 and 8.5) could be successfully applied for high-precision PDA micropatterning. Moreover, the effect of antioxidants and purging of the solution with oxygen and nitrogen was investigated. In all cases, no decrease of deposition efficiency was observed. The chemical nature of PDA was confirmed by locally recorded vibrational and x-ray photoelectron spectra. To ensure post-modification potential of MPL deposited PDA we demonstrated one-step deposition of micropatterns with trypsin. Obtained bio-functionalised surface can be further applied as a protein sensing active microelement. T2 - Laser Precision Microfabrication CY - Dresden, Germany DA - 07.06.2022 KW - Polydopamine KW - Two-photon polymerisation KW - Micropatterning PY - 2022 AN - OPUS4-55064 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Topolniak, Ievgeniia A1 - Hodoroaba, Vasile-Dan A1 - Benemann, Sigrid A1 - Pfeifer, Dietmar A1 - Sturm, Heinz T1 - Novel Boehmite-embedded organic/inorganic hybrid nanocomposite: cure behaviour, morphology and thermal properties N2 - Hybrid materials have attracted growing interest during the last decade, particularly due to their extraordinary properties. Cycloalyphatic-epoxy oligosiloxane (CEO) resin was shown to be a good candidate as a barrier material for the encapsulation purposes. Incorporation of inorganic nanoparticles such as Boehmite (BA) into polymers was observed to modify their specific characteristics, in particular, thermal, thermo-oxidative and barrier ones. In this work, novel BA-embedded organic inorganic hybrid nanocomposite material was engineered by combining the advantageous properties of hybrid polymers and nanoparticle enhancement effect. Impacts of particles on the photocuring kinetics, degree of crosslinking and the resultant changes in the thermal properties of the cured films were investigated. CEO synthesis via condensation reaction was confirmed by 1H and 29Si NMR. The particle distribution within the films was verified by SEM including transmission mode coupled with EDX elemental analysis. Photocuring kinetics and thermal properties of the films were studied by in situ FTIR spectroscopy and DSC with TGA, respectively. T2 - Deutschen Physikalischen Gesellschaft CY - Berlin, Germany DA - 11.03.2018 KW - Boehmite KW - Nanocomposite KW - Cycloalyphatic epoxy oligosiloxane KW - CEO PY - 2018 AN - OPUS4-44520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghasem Zadeh Khorasani, Media A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - Mechanical and chemical alteration of polymer matrix induced by nanoparticles in epoxy-boehmite nanocomposites N2 - Inorganic nanoparticles are used to improve the performance of epoxy as the matrix phase in fiber-reinforced composites used for aerospace applications. The effectiveness of nanofillers on property enhancement of thermosetting polymers depends on many factors including the interaction between the functional groups of nanofillers and the polymer reactants. In the current work, we study the effect of boehmite nanoparticles (BNPs) on properties of anhydride-cured bisphenol-A-diglycidyl ether (DGEBA). Dynamic mechanical thermal analysis (DMTA) and a high-resolution force measurement approach called intermodulation atomic force microscopy (ImAFM) were carried out to investigate the thermomechanical and nanomechanical properties of this material, respectively. It was found that BNPs lead to decrease of glass transition temperature (Tg) and crosslink density of the polymer network meanwhile significantly enhancing the Young’s modulus. Besides formation of a soft interphase near the particles, significant changes in local stiffness of polymer matrix far from the interphase was observed with ImAFM. Thus, boehmite induces long-range chemical alteration on the matrix. This effect has a higher impact on overall composite properties compared to the formation of interphase which is only a short-range effect. The local chemical evaluations on the soft interphase using an infrared-AFM method (NanoIR) revealed the accumulation of anhydride hardener near the boehmite interface. Based on these observations the effect of boehmite on the curing of epoxy is hypothesized to be governed by the strong interaction between boehmite and the anhydride. This interaction causes changes the ratio of reactants in the epoxy mixture and hence alteration of curing pathway and the network architecture. In future studies we examine this hypothesis by measuring the thermomechanical properties of cured epoxies in which the epoxy-hardener ratio is systematically altered and further comparing to those properties of nanocomposites shown in the current study. T2 - HYMA 6th International Conference on Multifunctional, Hybrid and Nanomaterials CY - Sitges, Spain DA - 11.03.2019 KW - Nanomechanics KW - Polymer nanocomposites KW - Boehmite KW - AFM KW - Epoxy PY - 2019 AN - OPUS4-50692 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epperlein, Nadja A1 - Menzel, Friederike A1 - Schwibbert, Karin A1 - Koter, Robert A1 - Bonse, Jörn A1 - Sameith, Janin A1 - Krüger, Jörg A1 - Toepel, Jörg T1 - Influence of femtosecond laser produced nanostructures on biofilm growth on steel N2 - Large area periodic surface structures were generated on steel surfaces using 30-fs laser pulses at 790 nm wavelength. Two types of steel exhibiting a different corrosion resistance were used, i.e. a plain structural steel (corrodible) and a stainless steel (resistant to corrosion). Homogeneous fields of laser-induced periodic surface structures (LIPSS) were realized utilizing laser fluences close to the ablation threshold while scanning the sample under the focused laser beam in a multi-pulse regime. The nanostructures were characterized with optical and scanning electron microscopy. For each type of steel, more than ten dentical samples were laser-processed. These samples were subjected to microbial adhesion tests, investigating bacterial adhesion behavior on the laser structures in comparison to polished reference surfaces. Short term experiments (<24h) were carried out to determine initial biofilm development. E. coli as a typical bacterium representing pathogenic bacteria and Shewanella putrefaciens as metal corrosive bacterium were used for biofilm development analyses. Bacterial cell adhesion was determined microscopically after DAPI cell staining (DNA staining). Comparison of the coverage areas between nanostructured and polished surfaces revealed differences in cell adhesion behavior and biofilm structure. T2 - E-MRS 2016 Spring Meeting, Symposium C: "Laser-material interactions for tailoring future applications" CY - Lille, France DA - 02.05.2016 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Biofilms KW - Steel PY - 2016 AN - OPUS4-36045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fortini, Renata A1 - Sturm, Heinz A1 - Meyer-Plath, Asmus A1 - Kehren, Dominic T1 - Development of a method for measuring the flexural rigidity of nanofibers N2 - Toxicological studies have shown that some types of carbon nanotubes may provoke asbestos-like effects including chronic inflammation and lung cancer. Inhaled carbon nanotubes may reach the deep lung tissue. Alveolar macrophages are responsible to remove such foreign objects from the alveoli in a process called phagocytosis. If a macrophage fails to uptake a nanotube completely, cell lesions give rise to inflammation. It is currently assumed that short, long and flexible, and granularly agglomerated (tangled) nanofibres are clearable by macrophages, whereas biodurable long and rigid nanotubes persist in the lung tissue. The flexural rigidity of nanofibres is therefore believed to an important material property that governs fibre toxicity and needs to be investigated. The present work aims at determining the rigidity of nanofibres by detecting their resonance frequencies using a Dynamic Scanning Electron Microscope (DySEM) setup. By depositing and fixing a nanofibre to an oscillating support, it can be excited to vibrations and treated as a cantilevered beam. This way, its elastic modulus can be determined via Euler-Bernoulli’s beam theory. Multi-walled carbon nanotubes (MWCNTs) were deposited on high frequency piezoelectric quartz crystals mounted on a scanning electron microscope (SEM) holder. When introduced into the SEM chamber and connected to a frequency-sweeping waveform generator, the quartz crystal actuates the deposited fibre. A lock-in amplified processes the secondary electron detector signal resulting from the electron beam modulated by the vibrating nanofibre. Whenever a fibre resonance is detected, the SEM image of the fibre is stored to identify the fibre oscillation mode. The found resonance frequencies and modes allow determining the elastic modulus according. Since the frequency spacing of resonances is predicted by Euler-Bernoulli, the mode number can be checked and elastic modulus values be averaged. A significant number of MWCNTs have been classified according to their level of rigidity. The applicability and reliability of the method will be discussed. T2 - International Conference on Multifunctional, Hybrid and Nanomaterials CY - Sitges, Spain DA - 11.03.2019 KW - Carbon nanotubes KW - Rigidity KW - Resonance KW - Nanofibers KW - Bending modulus PY - 2019 AN - OPUS4-49196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghasem Zadeh Khorasani, Media A1 - Silbernagel, Dorothee A1 - Sturm, Heinz T1 - Long range influence of boehmite nanoparticles on the nanomechanics of epoxy matrix used in carbon-fiber composites N2 - Boehmite nanoparticles (AlOOH) were recently found to improve properties such as crack resistance, shrinkage and compressive strength in epoxy composites. Concentration and surface modification of boehmite nanoparticles are key factors for abovementioned enhancements. To understand the underlying mechanisms, more detailed research of micro- and nanoscopic mechanical properties is required. The presented study aims to investigate the influence of concentration and surface modification of boehmite on the stiffness of the bulk epoxy by means of AFM-based approaches: Force-Distance curves (FDC) on the sub- microscale and Intermodulation AFM and amplitude-dependent force spectroscopy (ADFS) on the nanoscale. For this purpose, stiffness-maps of epoxy filled with boehmite, with and without surface modification (HAc-boehmite) were obtained by FDC. These measurements showed a slight increase in overall stiffness of composite with increasing the nanoparticle content. The stiffening effect was observed to be intensified with HAc-boehmite. Since the lateral resolution of FDC is not high enough to distinguish nanoparticles, this effect was assumed to be due to the inevitable inclusion of nanoparticles in the measurement. By using Intermodulation-AFM, yielding ADFS stiffness maps with the resolution of <10 nm, we were able to calculate the average stiffness of bulk epoxy without the interference of nanoparticles. It was expected that the stiffness of regions faraway from particles would be equal to neat epoxy. In contrast, the results showed a drastic increase in stiffness of epoxy with increasing boehmite concentration (0, 1, 2.5, and 15%) especially in case of introducing 15wt% HAc-boehmite. Another important observation was formation of a spatial structure with non-homogenous stiffness distribution in bulk epoxy with HAc-boehmite. The underlying mechanisms of described observations are not fully understood yet. One hypothesis is the local increase in crosslinking density which we aim to investigate in our further studies by combining Dynamic Mechanical Thermal Analysis (DMTA) and Intermodulation-AFM. T2 - Frontiers in Polymer Science CY - Seville, Spain DA - 17.05.2017 KW - AFM KW - Boehmite KW - Epoxy nanocomposite PY - 2017 AN - OPUS4-50688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina A1 - Silbernagl, Dorothee A1 - Sturm, Heinz A1 - Ghasem Zadeh Khorasani, Media A1 - Schönhals, Andreas T1 - Competition of mobilization and immobilization effects of segmental dynamics in epoxy/Boehmite nanocomposites N2 - The polymer matrix region near a filler surface, termed as the interface, witnessed increasing interest, due to its possible influence on the macroscopic properties of the nanocomposite. The interphase is expecting to have different segmental dynamic, as compared to the pure matrix, which can percolate into the entire system. Here, the segmental dynamics of epoxy/Boehmite nanocomposite was studied by Broadband Dielectric Spectroscopy. It was found that an artificial relaxation process is present in the nanocomposite, on the contrary to the pure epoxy system. It was assigned to constrained fluctuations of polymer chains in the interfacial region, due to the nanofiller. However, the overall dynamic Tg of the system decreased with increasing filler concentration, indicating higher segmental mobility. This was in accordance with Temperature Modulated DSC investigations of specific heat capacity of the system, which was found to increase with increasing filler concentration, up to 10 wt%, indicating increasing mobility of the polymer matrix segments. Surprisingly, for the highest filler content, the heat capacity decreases, implying a formation of an immobilized rigid amorphous phase in the interfacial region. T2 - Spring Meeting of German Physical Society CY - Berlin, Germany DA - 12.03.2018 KW - Nanocomposites PY - 2018 AN - OPUS4-44503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Derra, U. A1 - Mescheder, H. A1 - Winands, K. A1 - Emonts, C. A1 - Comanns, P. A1 - Krüger, Jörg A1 - Kirner, Sabrina A1 - Skoulas, E. A1 - Tsibidis, G.D. A1 - Stratakis, E. T1 - Mimicking lizard-like surface structures upon ultrashort laser pulse irradiation of inorganic materials N2 - The wetting behavior of material surfaces can be controlled by surface structures. We functionalized inorganic material surfaces, such as steel, titanium alloy and silicon, to modify the wetting behavior using ultrashort laser pulses (fs- to ps-range). The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. A combined experimental and theoretical study of the laser processing parameters (peak fluence, scan velocity, line overlap) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, grooves, micro cones, dimples, etc.). Analyses of the surface using optical as well as scanning electron microscopy allowed the identification of morphologies providing the optimum similarity to the natural skin of lizards. For mimicking skin structures of moisture-harvesting lizards towards an optimization of the surface wetting behavior, additionally, a two-step laser processing strategy was established for realizing hierarchical micro- and nanostructures. In this approach, a laser-generated regular array of small dimples was superimposed (step 2) to the micron-scaled capillaries processed before (step 1). Optical focus variation imaging measurements finally revealed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting properties. T2 - E-MRS 2016 Spring Meeting, Symposium C: "Laser-material interactions for tailoring future applications" CY - Lille, France DA - 02.05.2016 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Steel KW - Lizard KW - Wetting PY - 2016 AN - OPUS4-36047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fortini, Renata A1 - Sturm, Heinz A1 - Meyer-Plath, A. A1 - Kehren, D. T1 - Development of a method for measuring the flexural rigidity of nanofibres N2 - Toxicological studies have shown that some types of carbon nanotubes may provoke asbestos-like effects including chronic inflammation and lung cancer. Inhaled carbon nanotubes may reach the deep lung tissue. Alveolar macrophages are responsible to remove such foreign objects from the alveoli in a process called phagocytosis. If a macrophage fails to uptake a nanotube completely, cell lesions may give rise to inflammation. It is currently assumed that short, flexible and long as well as granularly agglomerated (tangled) nanofibres are clearable by macrophages, whereas biodurable long and rigid nanotubes may persist in lung tissue. The flexural rigidity of nanofibres is therefore believed to be an important material property that governs fibre toxicity and needs to be investigated. The present work aims at determining the rigidity of nanofibres by detecting their resonance frequencies using a Dynamic Scanning Electron Microscope (DySEM) setup. By depositing and fixing a nanofibre to an oscillating support, it can be excited to vibrations and treated as a cantilevered beam. This way, its elastic modulus can be determined via Euler-Bernoulli’s beam theory. Multi-walled carbon nanotubes (MWCNTs) were deposited on high frequency piezoelectric quartz crystals mounted on a scanning electron microscope (SEM) holder. When introduced into the SEM chamber and connected to a frequency-sweeping waveform generator, the quartz crystal actuates the deposited fibre. A lock-in amplified processes the secondary electron detector signal resulting from the electron beam modulated by the vibrating nanofibre. Whenever a fibre resonance is detected, the SEM image of the fibre is stored to identify the fibre oscillation mode. The found resonance frequencies and modes allow determining the elastic modulus accordingly. Since the frequency spacing of resonances is predicted by Euler-Bernoulli, the mode number can be identified and elastic modulus values be averaged. A significant number of individual MWCNTs were classified according to their level of rigidity. The applicability and reliability of the method will be discussed. T2 - Microscopy Conference CY - Berlin, Germany DA - 01.09.2019 KW - Carbon nanotubes KW - Rigidity KW - Resonance frequency KW - Nanofibers KW - Bending modulus PY - 2019 AN - OPUS4-49198 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fortini, Renata A1 - Sturm, Heinz A1 - Meyer-Plath, Asmus A1 - Kehren, Dominic T1 - Development of a method for measuring the flexural rigidity of nanofibres N2 - Toxicological studies have shown that some types of carbon nanotubes may provoke asbestos-like effects including chronic inflammation and lung cancer. Inhaled carbon nanotubes may reach the deep lung tissue. Alveolar macrophages are responsible to remove such foreign objects from the alveoli in a process called phagocytosis. If a macrophage fails to uptake a nanotube completely, cell lesions may give rise to inflammation. It is currently assumed that short, flexible and long as well as granularly agglomerated (tangled) nanofibres are clearable by macrophages, whereas biodurable long and rigid nanotubes may persist in lung tissue. The flexural rigidity of nanofibres is therefore believed to be an important material property that governs fibre toxicity and needs to be investigated. The present work aims at determining the rigidity of nanofibres by detecting their resonance frequencies using a Dynamic Scanning Electron Microscope (DySEM) setup. By depositing and fixing a nanofibre to an oscillating support, it can be excited to vibrations and treated as a cantilevered beam. This way, its elastic modulus can be determined via Euler-Bernoulli’s beam theory. Multi-walled carbon nanotubes (MWCNTs) were deposited on high frequency piezoelectric quartz crystals mounted on a scanning electron microscope (SEM) holder. When introduced into the SEM chamber and connected to a frequency-sweeping waveform generator, the quartz crystal actuates the deposited fibre. A lock-in amplified processes the secondary electron detector signal resulting from the electron beam modulated by the vibrating nanofibre. Whenever a fibre resonance is detected, the SEM image of the fibre is stored to identify the fibre oscillation mode. The found resonance frequencies and modes allow determining the elastic modulus accordingly. Since the frequency spacing of resonances is predicted by Euler-Bernoulli, the mode number can be identified and elastic modulus values be averaged. A significant number of individual MWCNTs were classified according to their level of rigidity. The applicability and reliability of the method will be discussed. T2 - EUROMAT CY - Stockholm, Sweden DA - 01.09.2019 KW - Carbon nanotubes KW - Rigidity KW - Resonance frequency KW - Nanofibers KW - Bending modulus PY - 2019 AN - OPUS4-49197 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghasem Zadeh Khorasani, Media A1 - Silbernagl, Dorothee A1 - Elert, Anna Maria A1 - Sturm, Heinz T1 - Studies on interphase formation of cured epoxy resin near boehmite surface N2 - The application of inorganic nanoparticles as reinforcement agent for polymer composites is constantly growing. Improving the performance of the material with desirable properties requires understanding of the interaction between polymer chains and nanoparticles and the properties of the interphase as well. Boehmite, a mineral of aluminum with basic unit of AlO(OH), is a novel and promising nanofiller which leads to enhanced performance of polymer composites. It has been recently reported that boehmite nanoparticles have reinforcing effect on epoxy matrix in carbon-fiber composites. It was primarily assumed that these improvements are due to very high Young’s modulus of boehmite particles. However, in our latest study we presented new values for the Young’s modulus of boehmite much lower than those reported earlier. This brings up the importance of interphase properties, e.g. the crosslink density, which can have the dominant role in the overall material property. Nevertheless, due to resolution limitations of conventional nanoprobing approaches, characterization of the interphase between individual particles and matrix is a challenge. In this study, the main goal is to investigate the interphase of the epoxy/boehmite nanocomposites using AFM-based methods. We simplify the three-dimensional nanocomposite system to a two-dimensional horizontally layered sample with a large and easy to access interphase area. For this purpose, 1µm coatings of hydrothermally synthesized boehmite are prepared as the substrate on which the epoxy is later molded and cured. AFM surface potential and force maps were obtained on the cross-sectional cut of epoxy/ boehmite sample. The results show unexpectedly a large interphase area (approx. 1 µm) with different electrical and mechanical properties comparing to bulk epoxy. The average force-distance curves from this region showed more elastic behavior compared to bulk. The underlying mechanism of this influence is not fully understood yet. Thus, further investigation on the interphase region using the novel Nano-IR approach provides more information about the chemical characteristics. Numerical simulation will give complementary information to understand the effect of nanoparticles on the crosslinking density of the interphase. This can be different to bulk epoxy due to either different local temperature gradients or due to a surface selectivity of boehmite towards the monomer molecules. T2 - ICCS20–20th International Conference on Composite Structures CY - Paris, France DA - 04.09.2017 KW - AFM KW - AFM-IR KW - ImAFM KW - Boehmite KW - Epox KW - Nanocomposite KW - Interphase KW - Nanomechanics PY - 2017 AN - OPUS4-50689 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -